Traditional manufacturers also know that they make money from maintaining cars. If traditional manufacturers make cars that last, they will go out of business.
There's a balance they have to strike. If you can't on average get 7-10 years out of a car with normal preventative maintenance, you won't sell many as both those who buy for the long term and the secondary market for used cars will avoid.
Didn't the Japanese basically win the U.S. market by making cars that lasted?