“...Seems to me, level 4 wouldn’t be good enough. They still would need to pass their drivers exam and be able to control the car at a moments notice....”
I think that’s precisely the problem - They DO pass their driving exams already.
I was at DMV a few months ago and observed a cohort of extraordinarily elderly people who all were taking (and passing) their driving exams. All had trouble walking and most couldn’t really even read the forms they were filling out ( copious help from nurses or adult children ) .
I want to be clear that the Elderly absolutely need mobility and deserve independence. I welcome the coming of level 4 vehicles because My 83 year old Mother will be liberated from the stress of crashing and getting lost. She‘ll be able to visit friends much more often. Level 4 would be a godsendf for her and millions like her.