> In fact their primary purpose is to keep kids locked up in one place for a big chunk of the day so adults can get things done.

I work from home full-time. Our seven year old son has a desk in the adjacent room with a laptop on it. He'd happily sit there using his laptop all day long instead of going to school, leaving me in peace to work in the office. So I don't feel like we really need school as a babysitter (although I acknowledge many other parents don't have my kind of job and so really do need school as a babysitter)

What I think we really need school for is to get him away from his laptop and into face-to-face interaction with other kids. Learning is quite secondary to that. (He's a smart kid and he learns a lot of stuff outside of the context of formal education.)