Markets work. But sometimes they take time. That's the uncomfortable lesson that proprietors of America's colleges and universities are learning. For many years, market forces didn't seem to apply to them. There was a widespread societal consensus that a college education was a good economic investment. Politicians gave lip service to the idea that everyone should go to college. No one should be stopped by a lack of money. There was historic precedent. The G.I. Bill of Rights vastly expanded college populations and helped build prosperous post-World War II America. Putting even more through college would make us even more...