Yep, you will eventually find them all.. We went through same thing with our brand new camper. First time I hooked up the black tank flush the only thing that got flushed was the bathroom floor. Factory forgot to put a washer in the fitting to the outside and it was 'flushed' alright. LOL I, like you found it easier/quicker just to go buy that $.50 washer and put it in myself... (Let the 'warranty' people start yelling at me)..
To be honest we all are pushing for more and more options on everything these days (trucks, trailers, houses, etc.).. More options = More problems no matter what it is. proof of my point? How many of your previous pop-ups had rear stabilizer switches and couches to go bad in the first place? (not picking on you, just using your example)
As long as it's not something major I consider it part of the process and won't be sending letters to lawyers/manufacturers anytime soon. But, I do understand the frustration.
Happy camping.