Of course, whether it makes sense to count Social Security and Medicare payroll taxes the same as income taxes in assessing the progressivity of the tax code is open to debate. Nominally, you're paying into a retirement program. The reason why the payroll taxes are capped at income of $110,000 is because the benefits one is eligible to draw upon retirement are basically the same for everyone.
What if you computed the progressivity with income of taxes paid into the government minus benefits received from the government?
Well, the problem there is, Mordant, that the right-wing is apparently unwilling to admit that the vast incomes of the wealthy are benefits received from the government.