Re: "so far caused by human error and inattention"
how much do they depend upon GPS/maps being completely correct?
Good question. I have experience of a road doing a 1 km deviation up a ravine and the road looking like Ω while the GPS said go straight ahead like _. The ravine was several hundred feet deep.
While I'm sure the google cars would recognise the road stopping without falling into the ravine, I'm not sure they would have any idea where actually to go instead. I can imagine them emergency stopped at right angles to the oncoming traffic in the wrong lane and the nav unit melting down in consternation while making meep meep noises.