Earlier quoted context omitted.
So how is the vexing situation resolved? Either the onboard computer must be able to manage 100% of all situations, or the human driver must have an option to take control to resolve it themselves. You can't have a car that makes human control impossible, and then gets itself into vexing situations. You'll be stuck there forever.
For nearly every mistake that human drivers make, a good way to prevent it is to slow down. Not every situation must be navigated at maximum speed. Robocars will be better drivers than humans, but slower will still be safer. I'm not talking about cars parked in the lane indefinitely because they're confused by some dirt obscuring the center line. If that had been a thing the Google cars would already have fixed it.
This is an important point, one where the comparison to aircraft doesn't work. Aircraft and the Apollo missions couldn't have a failsafe that just says "I think something is wrong, come to a gentle stop".