It also potentially opens up policy options, or at least makes them easier to choose.
Here in New York, the roads are filled with elderly people like this. Mental acuity aside, they do not possess anywhere near the reflexes or dexterity to drive a car safely. Nonetheless, they are out there on the roads every day. It would be a trivial issue to implement basic physical and mental acuity tests that should be required in order to have a driver's license. Unfortunately this remains implausible because of the lack of an alternative means of transportation available to these elderly people (which could potentially be provided by self-driving vehicles).
> As I was leaving the supermarket I watched her struggle to open her car door before slowly getting into her car. I sat in my car for a few minutes watching as she struggled mightily to simply back her car out of her parking spot.
That is your cue to stay away from such drivers for your own safety. Just like if you see an idiot swerving on the freeway. Or if you hear loud honking and cars braking there is probably something going on. An AV would likely miss such cues unless it was specifically programmed to do so.