Computers don't have fatigue. Ever driven for 12 hours? I have. I was so exhausted, I couldn't tell how much of safety hazard I was to everyone else. Humans fuck up like that.

Even if computers can only match humans at skill level, they will be at the skill level 100% of the time, no directions. (And they will probably exceed us in skill anyways)

Car accidents don't happen because people lack skill nearly as often as because people aren't at their best for just a moment. That's why autonomous cars will be safer.