Hi,
Retests on capability, periodically every 3-5 years and if age is a factor (scientific) then a cut off point maybe.
If unexperienced then (not many road miles since test) then some allowance unless shown to be unsuitable and risk to others.
Retraining?
Some experienced drivers even with age might be better than your (anyone) mother.
My mother was atrocious, ended after she wrote off her car into side of bus after losing control in a skid.
Sun light is mentioned many times, a case in the past a driver killed a child who was wearing a bright yellow jacket, judge said driver could not of seen cyclist as the lowness of the sun and colour of clothing...........................
Reactions - I noticed when I was in my thirties I had a three month period off a motorcycle and when I returned to riding I was not as sharp, made no errors as such but noticed that I timed moments not so well, due probably to the speed you could drive at on such a machine, Only equalled by very few expensive cars.
My father WW2 had a little red book, his test was short and lasted seconds IIRC, licenced to drive tanks of course.
My test passed after one lesson, but had driven the length of the country on holiday as a learner, and used to ride 12000 miles a year on two wheels so it was quite simple.
Tests on Capability would remove many what we can dangerous drivers, you know the ones you sit next to where you cant wait to get out and your legs ache thru trying to make holes in the passenger footwell
P.S. Local women killed outright when a driver ploughed into a shop window................in court he had history of incapability and was suggested to surrender licence to escape prosecution, which he did.......................
