not all convicts are in an open prison** and are allowed to e.g. work and only sleep in the prison cell. but this is not the default and mostly part of the rehabilitation plan at the end of the prison term.
your video is about one experimental facility, and while I think this is a Good Thing not all prisons have “no locks or guards”.
Norway’s system is focussed on resocialisation, though. see Breivik’s conditions of detention, probably not even thinkable within the US prison complex.
* started to reply before you edited your post
** as approach common in Europe, the Marshall Project had a series of articles about German prisons, in a slightly less excited style compared to Moore : )
