What drive less car can do and the system in the whole can do is to be able to know where and when a car is driving in the vicinity where normal human cannot perceive. So the situation you describe will not happen at all if those systems are in place. Actually, you just describe a scenario where it is preferable to have a system that monitors human error that could prevent accidents like the one you describe to happen.
Also I don't know whether you have been following tech recently, and if you have seen the intro to drive less car, you would probably seen or heard about the infamous laser and radars mounted around the car as shown in the article in the link: http://www.slashgear.com/back-to-basics-how-googles-driverle...
It is virtually impossible for the car to crash into anything because the car can literally "see" everything around it. Also the algorithms is smart enough to anticipate or plan an alternative path to prevent collision with the objects. You sounded like you have never heard or been following tech especially machine learning, so I forgive you, but you should do some research first before posting comments like this...