I'm going to follow after CapnMorgan (without the crazy, if you see what I mean) with my word: "Bureaucracy".
Public school is oppressive, totalitarian and a self-supporting system of mediocrity. While every college and university in the world has thrived on being cutting-edge and hip, everything High School and lower is in no hurry to change the archaic system it works within. To get people to send their kids to your school, all you have to do is be in the area. That's it. There's no incentive to change what they perceive as not broken.
School is a soul-crushing place where your teachers double as cops, they're all incompetent or power-tripping, and there are no limits to what they can consider crimes. All good times with your friends, learning and enjoying spending time with the few good teachers (who aren't just in it for a daily paycheck) are despite the school system, not because of it. If you enjoyed your school days, it wasn't that school isn't awful. It's just that you were lucky.