Just as a matter of interest, the U-Bahn lines 2 and 3 in Nuremberg are entirely automated - there is not even a figurehead "driver" in the train. The doors are opened and closed on a timer. There are sensors to detect anybody falling off the platform at stations.
It works well. For example, short trains run every three minutes rather than longer trains every six, given that there is no shortage of drivers. It still doesn't prevent the trains being sardine cans, though, in the rush hour.