If we're advocating 'extra' qualifications (as I just did above) I expect the whole thing will cost an arm and a leg for the administration and enforcement. Here in Norfolk, we have a larger-than-average proportion of elderly drivers, and the nature of our roads(quiet country lanes etc) gives them a false sense of security. They meander all over the place, and drive at a constant 40 MPH, whether the limit is 60 or 30! If we were to have a motorway, there'd be a massacre of these poor old folk. (I'm a 'poor old folk' too, but I like to think I drive extremely safely, as in 40 years I haven't had even a tiny prang!)
By the way (thread drift alarm) has anyone any experience of the famous 'Magic Roundabout' at Hemel Hempstead? (A very complicated road system with a sign like a scribble) You approach it, do everything correctly, and always, but always, end up going the wrong way around it. The locals find this very amusing, but it's highly dangerous.