Cars got better when they started using more automated manufacturing processes, shared components, and for the most part the cars are an assembly of pre tested, mass produced parts. RV's are basically hand made, hand wired, hand plumbed, and after assembly, each time you move it, it's as if your house has gone through a mini trembler. There will always be something to tweak, tighten, inspect, repair. It is part of the deal. All this does not however explain the status of the beast as it comes from the factory or as it sits on the dealers lot.
I've bought old and now new, and as I stated above .... It's always something.