One of the things I find ironic, is that when car drivers have to stop driving due to impaired physical and metal capacity, poor eyesight and general frailty, without the need for a driving test, insurance, or number plates, they can drive what are called 'Class 3 Invalid Carriages' on the roads among traffic at up to 8 MPH. (Vehicles with an upper speed limit of 8 mph (12 km/h) are Class 3 invalid carriages.) Their design and equipment means they can be used on some roads as well as pavements.
8MPH is about half the speed of a cyclist and a great impediment to traffic when on the road rather than pavements (where they're limited to 4 MPH). I live in a large village with a population of 20,000 or so, with lots of elderly people, among whom there are a disproportionately large number who, when they step out of their cars so frail that they're clearly not fit to be driving a car, yet if they were taken off the road, could be riding Class 3 mobility scooters. I guess the only saving grace is that they'd be less of a hazard to others that they would if still driving round in cars.
I'm 84 this year, so four years ago, to satisfy myself and other family members that I was still a safe and capable driver, (having passed my driving test in 1964), I did a 'Mature Drivers' Assessment' with the Institute of Advance Motoring. I was up to scratch with a few shortcomings and could have left it at that, but I went on to take the IAM Advanced Driving Course and Advance Driving Test, which is conducted by a serving police driving examiner. You are assessed on 23 aspects of driving, and on each one are classed as either 'commended, satisfactory, or needs improvement'. I was pleased to have passed, with 9 aspects judged as 'commended', and 14 as 'satisfactory', with detailed feedback on each aspect. The bottom line was: 'A good drive to a consistently high standard - Pass'. Throughout the test you have to give a running commentary known as 'spoken thoughts' so the examiner ir aware of how good your observations are.
I'm not 'crowing' about it - I'm just suggesting that to anyone who has been driving for a considerable time, I can't speak too highly about taking a driver assessment and the IAM course. (It might help keep me off a 'Class 3 Invalid Carriage' a little while longer!).