Here's a completely different question to ponder:
Why don't we have a national sales tax/VAT and do away with income, capital gains, SS taxes? By my calculation, the Federal budget is roughly $4.5 trillion (damn.....) and the US' GDP is right at $23 trillion annually. A national sales tax/VAT tax at, let's say, 20% funds every dollar of the budget (in a time where we're spending ~ $1 trillion more than we take in). Don't know about you, but I pay more than 20% in taxes every year when you include SS and Medicare (~7.5%). For those who don't make a certain amount, they file and get a refund of 20% of their income below that amount (sort of a standard deduction). So, just to make it 'fair' or 'smart' let's make it 21-22% sales tax. And that tax is on everything you buy - home, stocks, groceries, cars, cable bill, etc. If you make a profit, you pay 20%. If you don't, you offset income. But, no deductions from your paycheck every month. Each individual would have a CHOICE of how much tax to pay as it's directly correlated to how much you buy.
Higher income/'rich' people will buy more stuff and, therefore, pay more tax thus pleasing the 'tax the rich'/'pay your fair share' crowd. Lower income people pay less but still have some skin in the game (for a lot of them, anyway) thus pleasing the '47% of Americans pay no tax' crowd.
I know the political animals would NEVER pass such a thing as it takes the power of coercion via the tax code out of their hands. But, it makes a lot of sense to me (assuming the tax rate is correct, of course). US debt level is a huge concern (and is only getting worse under current tax code) and 70k pages in the US tax code is ridiculous. National debt is $30 trillion but promised-but-unfunded debt adds another $50+ trillion to that number. We can't continue down this road forever and what we're doing is not working.