That's what prison in America is, but that's not what prison either has to be, or is everywhere else in the world.
If your goal is to torture people, America's system is very effective. If your goal is to rehabilitate people and make sure they don't go on to commit more crimes, America's system is an abject failure.
Recidivism in the US is 55% after 5 years, as compared to Norway's 20%. Apparently not treating people inhumanely is a great way of getting them not to commit more crimes. [1] Who would have thought?
[1] https://worldpopulationreview.com/country-rankings/recidivis...