When it starts to cost the manufacturer more to have someone else find and fix their problems than to do it right the first time is when you might see an improvement in build quality. If the dealer had to report back to the manufacturer anything they had to fix on a new delivery and that report affected some managers bonus or pay you might see some improvement. But as long as the builder is insulated from the customer and the problems, nothing will get done.
It is fair to say all things have some issues upon delivery and it is how the dealer/manufacturer handles the problem complaint that will keep customers coming back. It is entirely different when a manufacturer consistently puts out crappy work that is obvious to the uninformed.