What do you mean a sales tax is no better than a flat tax?
Income taxes are in and of themselves un-Constitutional and inherently evil.
Not to mention our current income tax system is fraudulent from its inception.
Message to Republicans running for national office: Rid the nation of the Gestapo IRS and you'll probably get all of my support (unless you're a pro-abort gun-grabber).
You are correct that the federal income tax is illegal. The only tax that the federal government is allowed to impose is 10% on interstate trade for the purpose of maintaining a common defense. The states, however, can tax on anything.
Of course income taxes are NOT unconstitutional. Except to those who don't actually know what is IN the constitution.