Explain US Taxation

Quoth CookingWithGas:

I have three members of Congress (Senate and House) representing my interests. A citizen of the District of Columbia has 535 members of Congress representing his interests. The problem is actually that the capital is over-represented, not under-represented, and the lack of representation specifically dedicated to the capital is are partial solution to that problem.

Quoth dracoi:

40% of filers don’t pay anything that’s called “income tax”, but they do still pay “payroll tax”, which amounts to the same thing.