Possibly the company owners think why improve when we are just he same as the rest. If no one is demonstrably better or worse so why worry.
That is not how businesses work. ...well in theory. Most businesses try to find something different the customers will go for and grow sales. Ultimately the businesses are there to generated capitol growth to pay dividends to shareholders, whether publicly quoted or private companies.
If the shareholders were genuinely aware how their share of profit was being wasted by the amount of production line rework, scrapage, and warranty work, I'm sure they would want to appoint new directors with a remit to improve the reliability record of their products.
There really is no excuse for the problems we continually read about and see. Caravans have been around for over a century, That should be more than enough time for them to understand how to make them so they don't fall apart when they see a pothole. and leak when a spot of rain falls.
Reliability and quality is something that has to be designed into a product and the way its constructed, you can't paint it on after its built .