Here is a good start for your inquiry for added education:

Design Guidelines for Surface Mount Technology
by John E. Traister

https://www.amazon.com/Design-Guidelines-Surface-Mount-Technology/dp/0126974004/ref=sr_1_1

Read this book and you will learn something regarding the electronic industry, particularly material cost and mounting/design processes that have evolved past much of the SMT that was originally designed starting in the 1960s, adopted by most industries other than pinball by the 1980s, and transferred to pinball beginning in the 1990s, which is the focus in terms of timeline. Once you master this understanding, then ask me for more sources of reference specifically applied to current boards presently based on evolution. Specific background is required first.

Of course since you familiar with the electronics of the auto industry you will also understand the the same lifecycle component testing which is used and same level of reliability in terms of rate of failure after the 10 year period. They are essentially the same. Much less so for those of the consumable market on items such as phones, televisions, and stereos.

Best of luck on your route, unless your operation is home use, which I already clearly differentiated.

Be aware many Stern node boards are not backwards compatible and game specific.

Design changes have already occurred.
Stern has no incentive to provide aftermarket boards cheaper based on present market superiority.
The term remains "planned obsolescence".
No one can fully analyze either generation of Spike PCBs because there are no schematics available!

Look to the past for comparison such as the Whitestar period after they upgraded the Sega boards from the 90s using a similar design concept.
Looking further back Bally tried a similar consolidated board concept mindset with 6803 systems which failed with operators and were short lived, but components were not SMT. For decades there was little to no proper technical troubleshooting due to some lack of proprietary design review understanding.

All pitfalls on use of advancements of technology with reduced regard for RSD considerations.

Those that work on the games regularly from route operation recognize that Stern SPIKE titles will be in the garbage dump in 10 years, but until then they will remain "reliable".
Our company still has regular, periodic infant mortality failures within 3-6 months of initial operation based on volume sales (we even had a couple instances out of the box), which requires node board replacement of all types. Why? HEAVY operational play.

We do full burn ins for at least 3-5 days before location placement. No full MPU failures to my memory. Stern customer service remains good.
Lifecycle remains doubled for home use games on average based on board testing.
Personally, I will never own a SPIKE game ever, as it is more apt within the next 5 years to get dumped for support when Stern moves onto a new system and determines this is already obsolete. It's like throwing money into a toilet, and pulling the handle.
Home enthusiasts are better off using the P-ROC system from other manufacturers, as this design is schematic documented and the boards are cost effective.
If a person is a high volume operator, it probably does not matter, as the game will have run due course, made its money, and you do have to buy what tournament and pinheads want to play, meaning the "new stuff" in many instances.

There are no significant advantages of SPIKE over SAM, except to Stern themselves in overall cost of manufacturing both in parts, design, and speed of assembly.
It does not even have an improved diagnostic or menu system comparative for such an "advanced" system.
The reality is SPIKE was a step backwards in the Reliability-Serviceability-Durability (RSD) of pinball PCB design and game longevity.
It is like comparing the modern Valley Dynamo Zombie Baseball to an old WMS 1962 World Series (which BTW World Series has more features).
If you put them side by side, fully serviced, Zombie Baseball fails first from things like sheared batting assemblies and bent running man units.
It is incredible how cheaply these games are produced at times.

Technicians already know, and it would benefit the public to stop believing Stern propaganda.
Being "behind" in technology has its reasons, as part of the requirements are having to be able to fix what you own.
If an item is purely disposable/unrepairable, operators refuse to buy new equipment and manufacturers stop making games.
Enthusiasts need to stop thinking that these devices were initially designed for home use, as even today they have operators in mind.
The percentage of home users that understand the SPIKE operation system is very small.

I thought this was a discussion regarding reliability and design functions of the boards?
If we are discussing features now, SPIKE certainly has these perks.
SAM was a very robust designed game system, which worked well.
Personally, I would rather have a game that I know I can keep going, than one that has extra fancy sounds and video.
That is why I still own EMs too.

You are correct.
As long as new owners can get buffaloed, Stern will not change.
It is not like operators and distributors are unwise to the events around them, but they have businesses to run.
It is more likely that Stern will completely stop production of games, if the market falls flat, during the next pinball stall.
They already were last time anyway in 2009, and only one vote saved the company.
Stern has to squeeze out as much money as they can, when times are good.

The current overload protection sometimes does not trigger on node board shutdown, coil, etc, and node board fails anyway.
One of the common problems presently, along with boards to get destroyed by some electrical voltage that is outside the specific circuit. Essentially, in some cases, no better than any previous PCB design. This could be corrected by independent fuse boards, but that has been removed from the PCBs in favor of the onboard "smart" monitoring that was referred. It is not all always that intelligent.

One of the biggest design failures of Stern SPIKE is lack of primary fusing.

We have had 6 examples in the past 2 years where a short circuit was able able to bypass the computer "watchdog" software on the MPU and fried node boards. This is not an isolated incident. The example listed above is not that uncommon. It sometimes is just a matter of bad luck, and sometimes you and up spend a lot of money as it can take up more than one board, but usually it stops with the first. The highest cost to memory was around $1000 of boards to the company. Good luck with replacements, if they are unavailable.

If schematics were available, I could with others figure out where loopholes exist in design, but Stern does not want operators discovering where they cut corners, as it might hurt sales. I can't remit the number of operators that simple refuse to buy pinball at all today, simply out of reasons of affordability or market use.

I have been trying to caution others as a collector, enthusiast, and technician of the ongoing pitfalls of this flawed system. I am not "anti Stern", but do know the reason why Stern is doing what they are doing for simple cost reasons.

In many ways I look forward to the end of the latest pinball revival as this will force Stern to improve the quality of construction of their products in all areas. It has happened before and it will happen again.

Until then I remain resolute in my opinion, which shared by operators and techicians which have to accept certain aspects in order to pay the bills. Consumers do not, but education remains a choice.

Distributors don't often take hits for consumers, or they would not stay in business. They do try help resolve complaints or issues, if possible, within reason. It is called, "pointing the way". They will take returns due to damage in transit, or lack of proper function after set up. Those type of failures are built into the business model by a distributor for returns.

Distributors often do not say anything, if they become aware of design issues, say introduced by technical bulletin updates by manufacturers, meaning boards/parts. They expect the end user, whether home owner or operator to make the request directly. If parts are available, a game remains within warranty, distributors will help a customer. If the game is a year old or more after delivery, not so much. That is the business model. Some might call this "shady" as referring to Betson Enterprises out here in Portland by some , but that is being overly harsh. These devices remain quantified as "commercial" equipment, not consumer electronics. Game distributors are not Costcos of the pinball world. If it works, its yours. Operators go to the SOURCE, meaning to manufacturer to solve problems, unless a distributor provided a damaged product in delivery.

Distributors are not designed/expected to be full time repair shops, except in resale of refurbished equipment. They are not troubleshooting customer care centers, and many don't have the necessary experience/time to do it for the smaller ones particularly. They are SALES, first organizations.

Distributors ARE aware of the shortfalls of present SPIKE games, but have no direct solutions. No doubts about this aspect. They simply won't say anything, as if they did they would be out of business, or lose their contract with a manufacturer.

Stern has continued to provide customer service "beyond the call of duty" in most cases presently including technical troubleshooting, but don't expect that same level of care once a game is over 5 years old. They don't laugh, rather simply shrug shoulders. The earliest SPIKE games qualify for this consideration today.

This Stern topic remains valid, openly discussed by owners, operators, and technicians, and situation mostly unchanged.
SPIKE I / II systems remain suspect and will not improve in reliability, serviceability, or durability unless there are changes due to the sales market.
This is the followup Mark Schneider video, three years later.

I cannot speak every homeowner, but the 25+ technicians I work with regularly or converse, prefer not to fix Stern node boards.
This does mean they do not possess the skill, education, or proper equipment to do so.
Private techs are becoming more and more rare for many reasons, outside the scope of this discussion.
We certainly repair when we have no other options, especially when SPIKE boards are NLA, which has already happened.
I don't know many private collectors with hot air stations / microscopes and training, but I do know quite a few that pay others to maintain their games, averaging $75-120 / hour in labor which is realistic pricing.

SPIKE schematics and documentation remains insufficient in comparison to any previous pinball operating system, and electronic diagnostics remain practically non-existent. Essentially we have to reverse engineer Stern board designs to determine the shortfalls in design in order to replace SMT components, if possible. Direct suggestions to Stern for board improvements from SPIKE I / II where ignored in favor of reduced costs. All of this directly infers lack of interest for the design to encourage repairs. I do not know how to quantify this concept with statistics. Throwing numbers at the problem will not convince anyone, so this seems wasteful.

BTW, SPIKE I / II are not fully backwards compatible with changes that were not fully documented, and made intentional to promote obsolescence, not significant improvements. I am not speculating, but rather comparing the systems benefits and major features. Nothing wrong with technology advancements, but SPIKE II is not a step forward in integrated SMT.

What has held up a potential landslide of otherwise large number of failure complaints is the positive support of Stern customer service.
The technology overall is not new (SMD was opted by many industries in the late 80s), and the Stern SPIKE system is still in its half life stage presently.

I recognize the changes in today's pinball market and collectors may not care, and that is not in my realm of control.