SGV's (self guided vehicles) have been used in industry for decades. Modern passenger aircraft are self flying, humans only there for passenger confidence and to help the planes crash.
The problem with a driver-less vehicle that has someone in it, to take over just in case, is that they have to be awake enough to know what's going on - and be monitoring the vehicle enough to know if it's about to make a mistake. That means concentrating more than actually driving... So what's the point ? Driver-less vehicles have been tested in various forms for decades now, and the same problem always comes up - they only work when their environment is fully controlled and is inaccessible to pedestrians, wild animals etc.
