There is something like this in place. (Refer http://travel.state.gov/visa/immigrants/types/types_1322.htm... ). The DV Lottery annually gives out ~ 50,000 green cards to people from which historically there have been low immigration rates (No India/China). The accepted candidates are required to have at least a high school education which I am guessing is designed to make the likelihood that they end up in the streets lower.

It would be nicer to supplement something like this with a system that allowed people who paid $X or employed Y people to get a green card faster.