I'm not sure it is "all of them", but piecework is common in the RV business. It's not so much a "go home early" thing as it is a way to adjust for varying production levels. Everybody on a crew stays until the day's work is done, but on days when only a few are built, everybody goes home early. And with a smaller paycheck. There are also some separate shops within the factory, e.g. a cabinet shop or a fiberglass molding shop. Those guys have their own "day's work", i.e. some number of pieces to be built that day. They work asynchronously to the assembly line guys. So does the final inspection area.
They also use assembly line technique, meaning each workstation along the line has x amount of time to complete the assigned tasks before the unit moves to the next station. If the worker has a problem with one part of the task, he may have rush through the rest. The lower priced brands are typically produced on a faster paced assembly line, meaning less time allotted for each task and lower standards for "acceptable".
The labor cost goes directly into the bottom line pricing, which leads to differing MSRPs. The RV business is extremely price competitive, so nobody simply charges a higher mark-up for the same thing. If one model is priced lower than a seemingly identical one, you can be sure that the labor and materials were reduced somehow. The major question is whether it is in an area that is important to you or not.
), and it is not uncommon for things to come loose or break occasionally once the rigs start bouncing down the road. 
