Never is a hard thing to prove. Just as human drivers have limits, so does any autonomous system. It's quite possible that an perfect driver can become aware of

Never is a hard thing to prove. Just as human drivers have limits, so does any autonomous system. It's quite possible that an perfect driver can become aware of a problem with insufficient time to avoid collision, due simply to inertia and circumstance. An example: The autonomous car is driving happily down a residential street, tailgated by another car. A car pulls out of a blind driveway immediately in front of the autonomous car. The car must then make the choice between T-boning the car in front or slamming on the brakes and hitting the car behind. To remove the ability to swerve, let's add pedestrians in the sidewalk and a steady line of cars in the oncoming lane.