An RV, or any vehicle, is an incredibly complex structure to build and it is unreasonable to expect them to be perfect.
I have restored many Classic Cars and had them purchased by museums for their collections. I have also had some of my vehicles receive gold and platinum awards, and guess what........they were still NOT perfect. A 1000 point vehicle is very very rare, and this is from people that have every incentive to make that vehicle perfect. Even when cost is no object, it is next to impossible to have a 1000 point perfect vehicle.
Depending on the "standards" of the buyer, every vehicle could be picked apart to the point where it is just not possible for the dealer to correct all of the problems. The same goes for the manufacturer's inspection standards.
I am not saying that you should accept blatantly obvious defects, but you must use a little "common sense" when doing a vehicle inspection, which some people apparently do not possess.
Items that break AFTER delivery and use by the new buyer is a whole other topic and those defective items would never be discovered by the builder, dealer, or the buyer in a pre-purchase inspection.
Sometimes stuff happens and things break. Sometimes it is caused by improper installation, a manufacturing defect, or the buyer's misuse. The more complicated the vehicle, the more likely it is that something may break, or fall out of alignment.