(Endgadget) Uber really couldn't be more of a magnet for controversy. When it's not being banned or prompting sometimes violent protests from traditional taxi competitors, it's being scrutinized for the behavior of its drivers. The company added a panic button to its app in India after a driver was accused of raping a female passenger; another driver was arrested on sexual assault charges in France; and in San Francisco, one passenger was allegedly beaten in the head with a hammer following a disagreement over routes. And those are just a few examples. Today, the company is on the hook for yet another unpleasant incident, after a London driver threatened to slit the throat of a user who canceled their ride.