Quality control issues-curiosity

I have motor homes from three different msnufacturers. One I kept for only 9 months. Was paid to return to factory and fix numerous problems. Never was satisfactory. They are now out of business. Had three winnebagos. Two gas were great coaches, one, a diesel was an absolute Lemmon. Winnebago was still doing one year warranty work on it at the 5 year point when I got rid of it. Had 5000 moles dedicated to and from warranty work. I bet I talked to at least 100 owners of the same motor home, a journey,and no one had the same problems as I did. Moral to the story: it is not always the model or the dealer, some times it is just a lousy product caused by lack of quality production and control on a particular day or model or something. Not sure what