Freedom is just a tool to choose a different set of constraints
When someone commits a crime(official one), he is undoubtedly incarcerated. Why imprisonment? I mean there could be “n” number of other things that could be done. But since the ancient times, the Romans, the Greeks, the Hebrews, the Persians, the Egyptians, etc. most civilizations believed in physical involuntary confinement. Over the years, this basic ground idea of punishment hasn’t quite changed except for the rules guiding them.
People discovered it long ago, that freedom is one thing everyone craves for and if that be taken away, there is nothing left but misery. Prison constraints physical movement which will definitely stop many more movements, your thinking will shrink, your outlook will shrink, you will be unaware of too much, etc. There are many ways in which ones freedom is destroyed, prison being the blatant choice(for me).
On the other hand one has to work for fixed hours per day, do regular stuff, cook food, attend lectures, complete excel sheets, etc. What if any of these is against your will? At this very point of time, I would want to get out and go away for a month do things according to my whims and fancies, but I cannot(I would rather some day down the line). Don’t you think this is imprisonment but milder? Well, when there is this person who has the freedom to do what he wants, what if he chooses to do nothing to chooses to disregard freedom?