In Vienna it's fully automated between stations. The main reason it's not fully automated is because there are no automatically closing doors in the stations. U5 is going to get it though:
https://www.youtube.com/watch?v=VBDqq7rwLE0You can quite often see the trains operate fully automatic though when the drivers are changing shifts at the end of the line. The driver typically leaves and locks the train, lets it reverse itself and then the next driver continues: https://www.youtube.com/watch?v=0eyjqS9lvNA
