The logic of school choice seems obvious. If parents selected their children's schools, they would not choose bad ones, so bad schools would not be able to survive. Schools would have to improve or close, just as a store that offers poor service will lose business to a store that offers better service.
Here's my problem with that logic: I think it's highly likely that many parents will choose bad schools.
People often make irrational decisions. The decisions most often studied by psychologists over the last 40 years are financial, but in the last 20 years research has explored decisions made about sex, medicine, and a great many other subjects (see Dan Ariely's wonderful book, Predictably Irrational, for an account.)
Financial decisions offer a useful analogy because the success or failure of the decision seems straightforward: you make money or you don't; similarly, it would seem, schools teach kids or they don't.