I'm not interested in the incarceration rates in the US (the legal and social system is so messed up it's difficult to find a starting point - Europe is not different either for the record), the discussion is about what is a valid justice course of action.

Some crimes need physical intervention in order to protect society. It's just reality. For example, a thief that breaches private property needs to be punished, because not only did he steal, but he also caused a loss peace in society, which affects everyone.