I agree on retesting - my husband thinks a way of introducing it would be to make the insurance companies premiums for those who took a training course/retest for a few years, then make it mandatory. He might be onto something.
But I agree something has to be done. I had a near miss with this over Christmas, driving back from seeing a relative.
There's a motorway interchange near our house for three major motorways. It's fairly famous and aptly named and the changeovers are evil. Coming from one motorway to another, the slip road is a blind bend, single lane which becomes a dead end in a barely a hundred yards onto the new motorway.
I'm wary of the corner, and I always drop speed going into it, knowing there could be someone in front of me that I can't see. Fortunate, on this occasion.
As I cleared the corner, there was another car. I braked, then had to brake again, hard, as it became clear that other car was doing, at most, 25 miles an hour.
At 25, he pulled off the slip onto the inside lane on a major motorway. No indication, nothing, just a blind merge.
The car already on the inside lane, doing a proper speed (and definitely NOT speeding) had to screech and swerve.
Slow car appears oblivious. He trundles along, blocking the lane, and I'm running out of slip road, leaving me a choice of either stopping dead at the end of the slip until he clears out of the way and risking a rear end prang at ~ 70, with my 2 year old in the back, or chancing an incredibly risky jump across two lanes of motorway with no real chance to accelerate until I'm in the middle lane, which I did, scraping away from another by inches when headlights in my rear view gave me no choice.
I'm a good driver, and the road was quiet, thank God, and no-one was hurt - but that one driver nearly caused three major, possibly fatal accidents.
As I passed the car, my DH got a look at the driver. 90 year old, still doing 25, glasses like bottle bottoms, clutching the wheel, nose to the windscreen and fixedly staring straight ahead.
And here's my real issue - arguably, had any of those accidents happened, they'd not have been recorded as his fault, but ours. Unless we could rpve the speed he was doing and the failure to indicate, it would have looked like the fault of one the other drivers, when in fact he simply wasn't fit to be driving on the motorway if he wasn't prepared to be a) driving at a proper motorway speed, b) correctly indicating his movements or c) using his hazard lights to warn of non-standard driving!!