T R Reid said this quote

“ Does the flat tax work?...The flat tax works in a country that is a former Communist state, with no investment capital, and low wage rates, which needs to build a capitalist economy from a base of approximately zero. The flat tax works if people are willing to pay a 20% sales tax on everything they buy to make up for lower revenue. The flat tax works if employers are willing to pay 34%, or more, in Social Security taxes for every employee they hire. The flat tax works in a country where almost everyone has the same amount of wealth so there's no need for the distributive effect of graduated rates. And if all these conditions are met, the flat-rate tax will probably work as long as the economy is on a path of steady growth. ”