The task of driving was designed around human abilities.
You can’t easily substitute another component for the human.
It is easy to automate trains. Not so much with cars.
No argument. I should have been clearer. A GPS device will devise what it thinks is the optimal path, without regard to actual conditions, for instance a stalled car blocking a lane. An autonomous vehicle should sense the stalled vehicle and drive around it.
One place where autonomous vehicles fail is in anticipating the decisions of human drivers, who often act irrationally and illegally. Humans unconsciously take that kind of behavior into account.