I didn't vote for Mitt Romney, nor Obama, thank you. My candidate was a Libertarian. Nice try though. :)
The government collects no interest if you have your withholding setup correctly. Regardless of the category, it still disputes the claim that lower income earners are paying more... they aren't.
And yes, many people do get more back than they pay in. That's what the Earned Income Tax Credit is for many (not all since it adjusts based on income). The less you make, so long as you earned income, the greater the credit is.
For example, say someone makes $14K per year with one child, and they are a single mother head of household. They get a $3,169 credit for 2012. The first $12,750 of ADJUSTED gross income is taxed at 10%, which they will fall under. So say their adjusted gross is at the high end of the 10% bracket and they pay $1275 in federal income taxes.. yet they receive $3169 in credits. They've just gotten a refund check larger than the amount they paid in. This doesn't even factor in money received indirectly from other government programs they qualify for at poverty income rates (food stamps, for instance).
Do a lookup on negative tax systems and the EIC. It qualifies as one.