If you have taken factory tours you can readily see why so many problems crop up. Some of course are much better than others. I well remember my tour of "Travel Supreme". They check and re-checked everthing. They had a roving inspector who randomly picked units to give them a tough inspection. No I never owned a Travel Supreme.
If someone got behind or had a problem on the line. The line stopped and every one working on that rig at that time helped solve the problem. They also used good materials and design to make a quality rig.
At another major manufacturer, (speed), was all that counted. I saw workers run screws through thin walls. The screws missed the framing all together. The work floor was a junk yard, as was the general working area. When we finally got to the final inspection area it was a joke. They plugged in power just long enough to see if lights or motors started. Then unplugged them for shipment to dealer. I saw wrinkles in the graphics on the outside of the trailer. Wood chips all over the inside of the trailer. I noted that there was substantial warp in the wall right at the entry door. You could see daylight through it. I asked about it and was told the dealer would fix any problems.