"Lets suppose the US had a 25% flat tax, then I would agree with you that it is unfair and regressive. On the other hand, the present system is regressive anyway. Working and middle class people are easily paying 30% in taxes, while it isn't atypical of wealthier people to pay less than 10% in taxes.
What I'm talking about is a dramatic reduction in government spending, and a low flat tax of something like 15% (and that is on both active and passive incomes). Furthermore, there could be a tax floor, meaning that only something over x amount could be taxed (relieving poorer people)."
A flattax is always bad for the poorer part of society, as the taxes have to cover the expenses. Therefore, they pick a percentage that fits that covers it. This percentage is always higher for the poor people than before the introduction of the flat tax.
Besides, scaled taxes are a good thing for the national economy too. Not all the money that's been made gets spended. A flattax would mean the rich would get a lot more cash, wich they'll save, in the best case in a bank where it can be used to fund investements (wich isn't as good as direct consumption), but it could also be moved to banks elsewhere, status symbols (like proper art, wwich oftenly originates from beyond the national borders) or real estate in a foreign country.
Scaled taxes keeps the money revolving, and keeps the poorer part spending too, wich benefits them, and keeps them within the economical system wich needs them spending. The '30s economical crash was induced by a large group that couldn't buy enough things anymore, and a small group that had enough money to buy whatever they wanted. This leads to overproduction, and economic downfall.....
God: Behold ye angels, I have created the ass.. Throughout the ages to come men and women shall grab hold of these and shout my name...