Yes SS and Medicare are taxes EVERYBODY pays. BUT there are 47% who pay nothing on the income they make, the wages they earn for doing some form of labor.
Because the tax code reduces the tax on lower incomes, offers deducts for spouse, kids, etc., when all the numbers are added up, all / most of the money collected in taxes solely on the income portion of the paycheck, is refunded.
As for the $927B vs. the $315B you are comparing apples & oranges. Your argument is invalid.
And if your were a college student, with a part time job and filed a tax return you would know low incomes pay next to nothing in taxes for income earned .