One of the things they point out is how structured this kind of freedom actually is, despite the shallow view that emphasizes "freedom" from coercion normally found in schools.
Here's an excerpt:
Far from the “free” image with which we started this account, Summerhill school has invisible boundaries, powerful inspections, binding agreements, and redemptive public rituals, as well as a set of visible sanctions that prompt and reinforce acceptable ways to live together. These all act as an “outside-in” pressure that frames and disciplines interactions while developing identities and
relationships, yet always with the possibility of change or resistance. We have suggested something of the total nature of students’ engagement with these structures. Summerhill is a powerful mechanism, generating discipline from within, and without the coercive relations of a “normal” school. The school orchestrates a vortex of engagements, from which there is no “backing away”, as one student put it. Everyone is ‘in touch’ with everyone else, more or less.