Because Uber wanted that. Other self-driving car companies (like Google (or whatever they renamed it)) have put a lot more work into their systems and done a m

Because Uber wanted that. Other self-driving car companies (like Google (or whatever they renamed it)) have put a lot more work into their systems and done a much greater degree of due diligence in proving their systems are safe enough to drive on public roads. Uber has not, which is why they've been kicked out of several cities where they were trying to run tests. But Tempe and Arizona is practically a lawless wasteland in this regard and is willing to let Uber run amok on their roads in the hopes that it'll help out the city financially somehow.