All this talk of re-testing is simply not going to happen. The system can't cope with the current need, never mind re-testing all those that have already passed.
There are approaching two million tests a year and around half of these are passes, so in five years time there would be an additional burden of 50% if there were a five year re-test period, without even considering the tens of millions of current drivers. So, let's assume there are twenty million of those - that is another 200% of the current workload if they all have to be tested within five years, and repeated ad infinitum.
It doesn't pass a simple sanity test, and even a ten year period is still far too much.
In any event, the standard of driving needed to pass the test is no challenge at all for the vast majority of people who have been driving for a long time. Testing would achieve nothing.
A crackdown on the senile few and those with other health problems that affect driving (like eyesight) would be far more effective.
There is more reason to ban all under 25s than there is to ban the elderly, and that isn't entirely reasonable or sensible either.