I think it's a combination. Some people expect perfection, some expect performance, and some take whatever they get. Those in the latter two categories are likely to do some repair work themselves, especially cosmetic issues, and not make a big deal out of it.
Having worked retail, I can say that "display models" get a ton of really lousy treatment. One of the problems with RVs is that pretty much every RV on the lot is a display model. With an auto, you take a quick look, you take it for a test drive, you decide if you're going to buy it or not - you may open the glove box, but not over and over. With an RV, you walk around inside, you open and close cupboards repeatedly, you try out the appliances, you lay down on the beds, you sit on the chairs/couches, your kids are doing the same - you spend a lot of time in the RV getting a feel for it. All that is putting wear and tear on the RV that an auto doesn't get.
Then there is the lack of manufacturing standards and the ability to demand those standards. Since lemon laws came into effect, a poorly made auto is no longer "buyer beware". The buyer has legal recourse that affects the dealer's (and the manufacturer's) bottom line. This legal recourse is pretty easy to put into effect. By contrast, RVs have no such easy remedy - it's still buyer beware. As more and more people are getting into RVing, manufacturers are pushing out product faster and faster - this speed is creating defects in the quality, but manufacturers see it as "the dealer can correct it on warranty" because they don't face the same risk of having to buy back the RVs under lemon laws, etc.
Then there is the expectation that an RV's interior should hold up the same as a house's interior. Many people forget to realize that an RV's interior is subject to small earthquakes on a regular basis - that will affect the durability of cupboards, trim, etc.