OK, let's have mandatory retesting every 5 years, with an automatic ban for anyone failing, as no doubt you and others would support.
Apart from making little difference to driver behaviour, in my opinion, where do you think it would get us?
Do you think the motoring lobby would take this lying down?
For, as sure as night follows day, there will be plenty of parties around who would be aggressively pressing for parity.
I wouldn't rule out an aggressive campaign for mandatory licensing, compulsory helmets, compulsory insurance, testing and retesting for cyclists.
Some of it could stick.
Be careful what you wish for.