Aren't self driving error rates already below human drivers? The fatality rate is extremely skewed by one incident in which the system detected an obstacle but wasn't allowed to stop the car because it was disabled (so... not a failure of the self driving aspect of that system) and another in which a partial self driving system warned a driver repeatedly to take the wheel, but they did not.
In both instances the problem was a failure to force action by the human drivers (or failed reliance on them). In the former case, the system would have braked, in the second, the system should brake instead of asking for help from the driver.
Meanwhile the overall crash rate for self-driving cars is lower, correct?