If there were really a higher tax rate that the wealthier people paid, then that would be fine. But in reality, they find ways to pay much less than the average, more poor person. That is why a straight rate that everyone would have to pay, no matter what--something like 10 or 15 per cent of income, would be the best idea.
I believe this is a very bad idea, because a lot of people would end paying less taxes than people with less income, it would become very difficult and costly to our government to detect the right level for everyone and then applying the correct level of tax for them. I believe we should be getting example from countries that have already applied a tax system like this and how they are getting a lot of different results. With a flat rate you azure that everyone pays consistently according to the amount they are expending.