Except the problem with a flat tax is, what about those who have no reportable income? What about those who live in the underground economy? Do they get to pay zero taxes while those who are working honest jobs send their money to Washington?
The FairTax would affect all citizens equally. If you don't earn any income--say you're living off an inheritance or you've got a lot of money saved up--then you beat the flat tax. And isn't one of the big problems of our current tax system that not every citizen pays?
Every person in the country buys things. There are ways you can avoid paying a flat tax, but you can't avoid shopping. With the FairTax, EVERYONE pays their taxes. Only fair, right?