I don't think it's safe to bank entirely on driving-as-transportation in old age. My grandparents and my partner's grandparents all live(d) in unwalkable places in the US, and it was hell on their families when they slowly lost the ability to drive. You somehow have to either drive them around yourself (expensive and a massive time commitment), move them in with you, or move them into a retirement community when they eventually lose the ability to drive safely around others. It's inevitable!