I agree that optimizing for vehicle cost and shipping shoddy software at the expense of human lives is the wrong tradeoff, and having different sensors that provide more coverage of situations is generally preferable if you can afford it.

But suppose you have a radar sensor that's faulty, and so it periodically thinks that there's something right in front of it, and so it causes the car to slam on its brakes. That's likely going to cause an accident if you're traveling at highway speeds. Does that mean that we shouldn't use radar in any circumstances? Of course not. But sensors are not infallible, and we need to keep that in mind when designing these systems.