Well, as someone who is approaching the 'feared' age you prescribe, let me try and give you an answer, but first of all, TWR, there are four question marks in your topic but only three questions. Here goes, from a personal point of you.
Yes, I do think I am safe.
Why ? Because I have just been approved so by the IAM, having passed the Institute of Advanced Motorists test, and the RAC Silver Standard, which are pretty both pretty stiff, and you have to retake the RAC test every year no matter what your age. Eyesight is checked first, by the way. Two questions I was asked during the IAM test test were, ' What were the last two road signs you've just passed ?' and, 'What are the colours of motorway cat's eyes ?' both whilst I was driving on the test, which takes about 50 minutes and covers motorway driving, rural and urban roads as well as parking and other manoeuvres, Highway Code test etc.
And yes, I would be strong enough to call it a day if I, or a proper authority, thought I was a danger to myself or others.
And finally, I don't know how many others would because I don't know everyone in the UK, I can only speak for myself.
I would add that when it comes to driving, as with most things, we should all be judged as individuals and not consigned to the scrap heap when a certain number appears on our personal records. Having said that, I would be completely in favour of compulsory driving tests every year ( or two) for the over 70s. But I think the stats show that drivers aged 18-25 have the greatest number of accidents, don't they ?
Cheers.
D