Can someone fill me in one the history with these NOS populated playfields? They seem like an odd replacement part for a company to offer/produce.

I get needing new backglasses for when some jerk smashes out the backglass on location and needing random small replacement parts, but the whole playfield?

I just don't get an operator replacing only a playfield if it wore out. I would think the whole game would be a mess if the playfield got worn out on location and by that time the operator would just want to get a whole new pin that would be more reliable and Bally would want you to buy one of the new titles they were selling.

Were these populated playfields just overruns when they were making the pins when they were not sure how many they were going to produce?

Did you see these types of populated playfields in the late 1980's and newer being made available?