Even if the self-driving cars are well coded, what about hackers? Imagine a virus that causes, say, a million vehicles to go berserk some Monday morning during rush hour. Or even just causes a million vehicles to brick themselves.
Yes, people can also go berserk, but you likely won't get a million of them doing so at the same time.
Have we learned nothing from M5 or iRobot or Terminator? Methinks 'tis about time for a Butlerian jihad.