I don't think mandatory education is like a prison any more than any other obligation to society. Everyone hates jury duty but nobody says it's prison, it's the cost of living in a society where justice is not decided entirely by people with the resources to become judges.

Public education might be unpleasant at times but it's the cost of living in an educated society. Which is so much better than dying of cholera, and that's what we would be doing without public education.

You know why we don't? Public education let normal people become doctors and scientists and engineers so we could treat disease, develop new medicine, and develop clean running water infrastructure.