The Fair Tax is a consumption tax which is a regressive tax method. Why would you want that? The less you make, the higher percentage of your paycheck you pay in taxes.
I can't imagine anyone thinking that is a fair or equitable system.
No tax is fair or equitable - obviously you think progressive taxes are "fair". Bottom line - make more, spend less, you'll be better off under te Fair Tax.
The basis of the fair tax is, you purchase the goods, you pay the tax. No loopholes, no special exemptions for favored groups, no tinkering with tax rates to implement a social agenda. It is still somewhat progressive, if that is what you favor, in that a tax rebate check is sent for a specified amount of base consumption.
That's absolutely the most fair and equitable system out there -- because most of the costs of government services are fixed, not variable. If one guy earns $25,000 and another one earns $250,000 and they both drive their cars 15,000 miles per year on the highway system (you can extend this rationale to any other government function), then there's no reason why the one earning $250,000 should pay 10x more in taxes for the same "utilization" of public infrastructure.
Even the U.S. government itself recognizes the idiocy of "progressive" revenue generation when it comes to dealing directly with taxpayers instead of through the convoluted labyrinth of the IRS. A first-class stamp costs $0.39 these days no matter how much freakin' money you earn.