Believe it or not, if you only make one dollar, they're still supposed to take 15 cents out of it. The current tax system is graduated because the rates change as you make more money. When a tax system makes the rich pay more, including deductions, it's called a progressive tax. Graduated rates are a bad idea because whether total taxes paid are low or high, low tax rates are good for the economy. The way to get the lowest rates on the most dollars is to have a flat rate.
Conventional wisdom is that the flat tax is an idea espoused by arch-conservatives.
But the first person I can remember proposing the flat tax was not a right-winger or a libertarian activist at all. It was Jerry Brown, the former Democratic governor of California, who is pretty far to the left. The system we have now contains innumerable loopholes designed to benefit specific people that powerful politicians want to reward. There's practically zero accountability for congressmen who write tax laws because they're so complicated. You could hide the Encyclopedia Brittanica in the tax code and no one would notice.