"federal income tax" is not even close to "tax burden of the federal government". Income tax is less than half the revenue of the federal government. Payroll

"federal income tax" is not even close to "tax burden of the federal government". Income tax is less than half the revenue of the federal government. Payroll taxes are huge, and disproportionately borne by the poor. Excise taxes are huge, and disproportionately borne by the poor. Overall, including state taxes (which are strongly regressive as well) the US has very close to a flat tax system, not progressive at all.