Socialism

I agree with your overall point, still I think there needs to be some context.

Here is the graph for USSR's prison population (I could only find it in russian on yandex, because search engines are so fucked up nowadays):

USSR really did have a relatively high imprisonment rate throughout its existence, and I think its punishment-focused penitentiary system was one of its worst sides. I'm glad that other socialist states are improving theirs, and I hope one day they can reach a point where prisons in their current form would no longer be necessary.

As an aside, I find it really interesting that there was a simultaneous increase in prison population in both USSR and the US in the 80s:

While in the US it was mainly caused by "law and order" politics popularized after the revolutionary movements of the 70s, combined with privatization of prison labor, I couldn't find any well-sourced explanations for why it happened in USSR.