"MS design design their own silicon - and all in areas related to DSP and machine vision - so why not Tesla? Hell, back in the eighties an Eastern Block company making lenses needed CPUs that they weren't allowed to buy from the West... so they made their own."
Tesla is an automobile manufacturer while Apple and M$ are computer firms so they are more intimately involved with the hardware. I wouldn't be at all surprised to hear that a former Eastern Bloc company had to make their own CPU, but what Tesla needs is something on the bleeding edge of technology, not a Z80 clone.
Through Tesla's acquisitions, especially the recent ones, it appears from the outside that Elon is a rampant control freak and micro manager. He IS well known as a nano manager and the exodus of key management and corporate staff all of the time for pat reasons makes it clear that he doesn't play well with others.
GM and Audi are way ahead of Tesla in autonomy right now and both have the capital to fund a vigorous development program.