Even in the land of opportunity and conservative think-tanks, the voucher program -- also framed as the school choice program -- has not been a success that it was theoretically meant to be. Greg Anrig has a great piece titled An idea whose time is gone that not only summarizes the most recent research on the voucher experiments in the US, but also explains the politics behind this program. Bottomline: The voucher program is unpopular, even in conservative states. In a referendum in Utah last November, "it lost by 62 percent to 38 percent—the eighth decisive loss for a statewide voucher ballot initiative. There have not been any victories."
There is a lot of stuff there in Anrig's article which you really ought to read, but I want to highlight a broad finding that goes beyond the voucher program, and which says something about the ability of a society -- even one as rich as that of the US -- to educate its poor children:
... as the sociologist James S. Coleman found in the 1960s, a student's family's income and the collective social and economic background of his classmates are by far the most important influences on his academic future. Not only do lower-income students tend to score relatively poorly, children of any background who attend high-poverty schools are far more likely to produce worse test results than they would in schools with primarily middle-class students.