And how would they know that a part is defective if it's not been put to the test in the real world?? No matter how many accerated tests they do on a unit, only a handful of problems will show up before it goes into production.
Take, for instance, computer software. If they tested every line of code it would take them 10 years, whereas if they checked 80% of the code, it would only take them 6 months. If you're the software company, you need to call it quits at some point in the testing. That's why there are more reliable software that are built on top of another piece of reliable software that software that's built from scratch.
The same theory applies to car manufacturing. They make a good chassis and built many different cars on top of it... (Accord, TSX, TL, Oddessey) (if you're a Toyota fan, then Camry, Sienna, 4Runner, ES) (Mazda fan: Mazda3, Mazda5, Mazda6 ... same engines ) If a specific part breaks, it's redesigned and put back in (ie software patches). When you get the radio replaced, you're getting a redesigned piece of the car that's not prone to the same problems as the original.
) If a specific part breaks, it's redesigned and put back in (ie software patches). When you get the radio replaced, you're getting a redesigned piece of the car that's not prone to the same problems as the original.