How about not charging anybody for prescriptions? Those who can afford to pay would pay through their taxes. . . . But they were part of your claim, when you claimed that people who earn more pay more - they don't necessarily. They do, however, have more spare cash to spend on superior health care.
That is exactly what I am arguing for. Are you playing devil's advocate again, as I have better things to do than explain myself again if so? I have already said that I was not talking about above the cap - until that point it is true that higher earners pay more than lower ones.
But how would they leave the NHS? They can't stop paying for it. That's fine! If they don't want to use it, they're paying for a service they won't use.
People can't leave the NHS now, but as I said, there is no saying that that will not be an option if the government is able to separate those who pay and those who don't, as a means test will require a change of system. There are already ways of staying in the NHS but paying to get better (or faster) treatment, and these could easily be extended into a 2 tier system, as has happened with dentistry. If higher earners have to pay the top rate of NI (regardless of whether or not the current contributions are high enough) as well as pay for prescriptions they might decide that they would be better off taking advantage of private schemes that would prescribe certain drugs but refer them to the NHS for more expensive ones. There are already 'half way house' schemes like that - cheaper than fully private, but offering access to a GP and (I assume limited) access to prescriptions.
Anyway, I've already said all of this. There's not much point in repeating myself.