Obviously there are some people who are too disabled to do this, but “OAP” is a pretty expansive term, Brumbies.
In Tokyo where I live, it’s usual for the elderly to ride trikes with their shopping if they no longer feel safe on bikes. It really helps with keeping elderly Japanese people on their feet and mobile and getting exercise for as long as possible, and means that adult children (=adult daughters, most of the time) do not have to spend their lives taxiing elderly parents around everywhere.
For the hard cases, when people really and truly are too disabled to walk anywhere, there are mobility scooters and the like, but by the time people get to that stage, it’s unlikely they will be fit to drive safely anyway, so designing societies around car dependency is merely going to result (as societies age) in ever-growing numbers of elderly people trapped at home, and middle-aged women spending more and more of their lives driving their elderly parents around from place to place.
People, including the elderly, need to walk and move for as long as they can possibly manage it - the average British over-60 gets nowhere near enough exercise.