Humans are terrible. The human eyes and brain are good at detecting certain things though that allow a reaction where computer vision, especially only using one method of detection, fails often. There are times when an automated system will prevent a problem before a human could even see it. So far neither is the clear winner, human driving just has a legacy that automation has to beat by a great length and not just be good enough.

On the topic of human drivers, I think most on the road drive reactively and not based on prediction and anticipation. Given the speed and possible detection methods, a well designed automated system should be excelling at this. It costs more and it more complex to design such a thing, so we're getting the bare bones of the best minimum tech can give us right now, which again is not a replacement for all cases.