Roads are a public good.
Having a road available to use, is worth almost as much as actually using it.
Not to mention all the positive externalities of a better connected country (more trade, business, economic growth).
You're costing X times more to the system because you're diabetic/obese/predisposed ? You should pay more!
That's how it sounds, and if we want to live like that we can go back to cavemen times, because we didn't built societies to play this silly game
The positive externalities created by trucks shipping food into cities massively outweigh almost all passenger traffic.
So charging by weight/road damage makes no sense.