Social security/medicaid taxes are fucking rough, if you've ever worked a low income job and seen how much of your money went to that shit with no way of getting it back you'd know what I mean.

Also, social security/medicaid double dip and your employer has to pay the same amount you do, which means they pass that cost onto you by lowering your wages. This is another hidden tax that is not counted in that 40% figure. Also, like property and sales tax, it's both somewhat regressive (poor people pay bigger %) and a much bigger proportion of what poor people pay than what rich people pay.

https://taxfoundation.org/payroll-income-tax-burden/