I see a dangerously double-edged argument. To base the deriving of society’s expenses per a person on that person’s earnings is odd. Especially if you limit your view to the 99% of population who are either just normal employees, or their dependents, or even welfare receivers of some kind. If I am making 50% more in my 30s than I did in my 20s - do I really cost more? In my 70s I would likely make nothing, except the pension, but my healthcare bills would grow.

So taking your point to extreme - should my “taxes” (on what?) be the highest in my 70s?