Gill Pratt, the head of auto-car R&D at Toyota, has been agreeing with you since he joined in 2015, essentially saying that auto-cars must be better than very good human drivers in all parts of driving, even those that occur rarely. But mastery of those rare events that will be hardest to acquire, since few useful examples are available from which to train. Thus those last few yards to the goal will add years to the development time in subtle ways that will be maddeningly invisible to the public -- until seemingly clueless crashes arise on public roads, perhaps like the one last month which terminated all of Toyota's auto-car testing on public roads until further notice.