Last night I had a ride home with someone who suddenly, very suddenly because of an "age-caused" car accident has to take care of parents. One of the things is that many continue driving yes, legally, when they shouldn't be. Their reaction and judgment are faulty.
Many elderly are "offended" when they're retested before being able to renew their drivers license, but it seems that those precautions aren't enough. I have a friend who discovered that her father had continued driving even when he was functionally blind. Her mother would tell him when to slow, stop and turn. Finally "the kids" made them give up the car.
My favorite episode of "Everyone Loves Raymond" is the one in which they discover that his father, Frank, shouldn't be driving.