OK sure, but if you're going to that, and not eliminate (or reduce) any current gov't programs then you have to raise taxes. If you want't to give, say 10k to each american that's 3.1 Trillion dollars which is more than the US gov't raised in taxes last year.
Well, yeah, you'd raise taxes, to the point where it nets out on average. You raise everyone's taxes by $10k on average, and give everyone $10k. At the average income it's a wash. At the low end people were already getting welfare and not paying much in taxes, so it's a wash for them too. At the lower-middle-class to middle-class level it reduces the disincentive to work and makes people better off. The only people who really lose out are at the very top, people who make so much money that any percentage-based increase would swamp the fixed gains (which is why, I would guess, they oppose it).
The math doesn't work.