As DaveH said, all the manufacturers have written warranties. Here's Stern's written warranty (from the TMNT Pro manual, but I don't know that it's changed much over the years):

Stern Warranty.jpg

Here's JJP's written warranty (from the GnR manual) [EDIT: May 2021 Edition]:

JJP Warranty.jpg

Whoops, I misread, the current warranty is dated March 2121, not May 2021.

And here's CGC's written warranty (from the Monster Bash link on their website):

CGC Warranty.jpg

As written, Stern and JJP provides no coverage for playfield or cabinet defects. CGC's written warranty is more expansively worded and presumably includes playfield and cabinet defects for 3, 6, or 12 months, subject to interpretation of the phrase "normal wear and tear."

That said, Stern has a long history of providing "warranty" support for components that are expressly excluded from the written warranty, often years outside of the written warranty period. I haven't owned a JJP but I'd guess they have broadly similar policies. What that means for playfields is both uncertain and evolving, and seemingly hinges on how bad your individual situation is, how wide-spread the problem is (i.e. how expensive it would be for the mfr. if it starts covering your specific issue), and how loudly and publicly you complain.

As MrBally said, these warranties read like they do because of the commercial/route background of the business. Operators didn't expect and weren't willing to pay extra for the types of warranties that are standard with consumer electronics. And home consumers haven't raised a huge fuss because of the informal/"good will" coverage that's extended for most things. Could one manufacturer gain an advantage by putting their actual existing practices into their written warranty, or by providing express coverage for playfield clearcoat issues? Maybe, but would that offset the added cost of providing additional coverage, and lost sales due to price increases necessitated by increased coverage costs?

Huh, that does look like a significant change. The GnR manual I snipped from is dated May 2021 so maybe that's brand new language, maybe designed to mirror Stern's written warranty?

Whoops, I misread, the current warranty is dated March 2121, not May 2021.

JJP playfields have had these same problems for several years now, you'll see that if you go back and read the threads on Wonka and POTC playfields.

But JJP apparently just this March (or sometime between this March and last November, anyway) made major changes to the written GnR warranty that removed coverage for the playfield. I'm not a warranty lawyer, but if I received my game before the change I'd argue that I'm entitled to the old warranty (which as I read it would cover the playfield, though I guess that all depends on when they date the invoice). And if I preordered before the change but haven't received my game yet, I'd consider demanding a refund of my deposit based on material changes to the deal that I didn't agree to.

Customers may also have been expecting JJP to take the same approach with GnR playfield defects that it did with Wonka and POTC, where it seemed like at least some people were able to get replacements.

Fair point, but I'm not correcting my (incorrect) correction - there has to be a limit!