I think I already answered a question today, with something like "There is rarely any point in asking 'why' with language questions". It's an interesting observation, but I don't think there is any reason for it. Like most things, there may have been a reason, but it would have been lost over time.

The reason for this is because schools and churches are institutions, just like hospitals and prison. Cinemas and theaters are places, so they take 'the'. Therefore, institutions do not take 'the' and places do. Denis, I hope this is helpful. What a great question! Brandy