The international evidence shows that private provision of education is often better but never worse than public provision. That there is so little private provision — not just in the U.S., but anywhere — can seem like a puzzle if you happen to think policy will tend to reflect the preferences of a benevolent technocrat. As Carney's piece below shows, powerful entrenched interests may have a stake in making sure private provision stays crowded out. So they'll do whatever it takes to make sure only rich people can afford to send their kids to private schools, maintaining a cartel in control of supply for the rest of the population.
Why else might private provision be so rare? Or, put another way, why might there be such a strong interest in maintaining government control over the supply of education? In a recent working paper, Harvard's Lant Pritchett and Martina Viarengo argue that this is explained by, among other things, the desire of those with a stake in government institutions to control the socialization of children. They build a model that illustrates how the the aim of controlling socialization can help explain the pattern of resistance to private provision, even in places where it is clearly vastly superior. I find this pretty intuitively plausible. One of the first arguments against vouchers, tax credits or other systems of publicly-financed, privately-provided education is that taxpayer money should not go to schools that teach this or that allegedly malign belief. It just so happens that, on the way to making certain that children are not taught that the world is 6000 years old (which would obviously neutralize one's ability to earn a living as a middle manager), children are also imbued with a certain nationalistic civic piety and the belief that, say, FDR saved capitalism from itself. Who knows what chaos might otherwise ensue?