They absolutely do! Earned Income is a refundable tax credit - 47% of all Americans pay no net income tax, and some receive a refund in excess of any taxes paid.
* excluding payroll tax deductions, both personal and employer paid (which is effectively still a tax you're paying). They also pay sales tax, which isn't an income tax per se, but when you have to spend every dollar you make to survive, it might as well be.
