What if my rate is 51% + 51% = 102%? (Unrealistic, yes, but gets to the heart of the "fairness" argument)
How am I suppposed to pay 102% of my income? Is that sustainable?
But if my state taxes me 51% of 100k, and there is SALT deduction, my federal taxable base is 49K instead of 100K, and I am now actually paying 24.9K instead of an impossible 102K.
Taxes are NOT service payments, they are a legal obligation, a good portion of which (rightly) pays for things you may not directly benefit from. It's in a completely different category than for-service healthcare, at least in my opinion.
Its amount is not also directly tied to how much money you make. If you know your income you could theoretically budget for such expenses.
Also, I believe healthcare premiums are in some (most?) cases tax-deductible, though this is somewhat besides the point.