What isn't being taken in to account the change of behaviour of other road users when automated cars are in the majority on the roads. Most pedestrians realise that stepping out in front of a car could mean death, even if it isn't speeding because you have to take a gamble that the driver is paying attention. When they think a driverless car will always see them and stop in time, then no more waiting for pedestrian crossings, they will just step out in to the road at anytime, and traffic will just stop.
So if you are in a driverless car get used to hanging off the seat belt every few seconds as a pedestrian or car with a driver decides you'll be the one to stop. I was going say pedestrians, cyclists or cars, but around Cambridge parts, cyclists already do that.