I'm a fan of flat taxes and consumption taxes as a replacement. But it's not really an option. -XC
Flat tax doesn't really work either. It taxes all people equally, but not all people are equal, at least economically. 10% to someone who earns $100 is a lot more in terms of buying power than 10% to someone who earns $1000. Consumption tax can work in the U.S. It did for over a hundred years before income tax was introduced. I think of it in terms of how people are disciplined. Negative reinforcement only encourages them to avoid getting caught. Positive enforcement is great in concept but how do you put that into a tax system? Not possible, so like I stated before tax based on who deserves it? People avoid taxes by finding loopholes or plain lying. How do you lie to a consumption tax? The only thing I can think of is black markets, but a black market for most things already exists and doesn't really threaten legal sales (i.e. piracy, bootlegs). If people don't want to pay the tax they can't get the goods.
Sometimes it's important in a democracy or republic to have a 'fair' tax. If you tax by efficiency you can end up with an 'unfair' tax. Remember any change to a government has to be brought about by the people; directly or indirectly. If you ask the people who they want to tax they will say the rich, because the rich are outnumbered 10 to 1 in even the most prosperous parts of the country. I don't think it's fair to let popular vote decide anything because you end up with a large minority being unsatisfied (see "Tyranny of the Majority").