Which one is supposed to be prison-like? Both just seem like utilitarian architecture to me (and so are prisons I guess). You don't want students to have to walk out in the elements between rooms in the middle of winter in New York, and you'd want to maximise the number of windows that classrooms have (since that's where students spend the majority of their day), so where else would you put hallways?

I suppose you could put windows between the classrooms and hallways, but those have their own associated problems to overcome: increased noise, more windows for students to break, safety in emergency situations, etc.

As for non-connected classrooms, where you need to walk outside to go between rooms, I've always thought that was to solve the same problems. Cheaper to build/renovate/modify/expand, easier to clean, less noise and fewer students running into each other.