Because Uber has no fucking business messing about with autonomous vehicles.
I mean, if you're qualified to work on a self driving car, there are plenty of companies that will be happy to hire you. At Waymo you can work with people who invented the techniques you'll be working with. At car companies you can work with people who have been doing industrial robotics since industrial robotics has been a thing. Or you can go to Uber, where management creates workplace drama on purpose because social darwinism or competition is always good or some business cargo cult thing, get puked on by coworkers who drank too much company-supplied wine, awkwardly pretend not to notice your boss and the new intern having sex in a conference room, and get the stigma of working at the tech company even hackernews cringes at.