The driving test was introduced in 1937 so the persons you are refering to as not having passed a test will now be at least 85 years old,although many elderly people of this age have passed a test as few could afford a vehicle in 1937.I have 2 elderly parents both 86, they live in a remote area, and their cars are their only means of transport.Ok they drive slow but are sensible,don't use motorways or fast duel carriage ways but mainly country lanes.Ask any insurance company where the biggest risk of bad driving is and I think the answer would be somewhat different to the picture painted here