If you look at the build quality of a Chevy vs a Ferrari I am sure you will see a quality gap. Each is built to different levels of expectations.
The RV industry concentrates on parts out the door. In my TT I have seen screws spanning gaps, cabinet doors hard to close and a few other other items that indicates a "good enough" attitude.
That said a lot depends on the target market, if you are a serious bicycle rider, only a carbon frame will do. Most folks will not pay that much for a bike. If you use your TT eight times a year to visit places close by on your limited budget and two week vacation, your needs are different than a hard core boonbocker.
The industry builds what will sell, the bulk of which includes "good enough" assembly.