Remember, the system has to be built to cope with not all likely inputs, not even all potential inputs but all possible inputs - and that starts to get extremely difficult and costly. It is easier and usually safer and more effective, for the system to pass the bag of bolts to the flight crew.
That is a justification to pass the buck and not a technical argument. One of the more troublesome aspects of making the computer the pilot is the issue of accountability. Right now "pilot error" is an easy out for the accident investigator. Take away the pilot and then who is to blame---software engineers? The software designer? A coder? Do these professionals now need to carry liability insurance?
But if one's first concern is
safety then for every hero captain one has to balance the goats. The question isn't whether the computer will make errors--it will--the question is whether overall the software will make less errors than humans. And that is true or will soon be true.