Because total tax expenditures are far from just income tax. There's property taxes, vehicle taxes, gas taxes, "christian sin" taxes, lottery (which is a tax on stupid people), social security tax, medicare tax, sales tax, specific item/service sales tax, city taxes, county option taxes.
And that's not even remotely the amount of taxes on businesses that raise the price of goods secretly to compensate the taxes hidden.
And also, even illegal immigrants pay these taxes. They aren't even exempt. And many use fraudulent SSNs, so taxes are taken an applied to those SS accounts, but the illegals never use them. Yet more money for the coffers.
But some percentage isn't paying any of one specific tax.
Whatever.