If you don't lock criminals away in miserable conditions, victims and their family members turn toward private punishment. People will get revenge. It can be of

If you don't lock criminals away in miserable conditions, victims and their family members turn toward private punishment. People will get revenge. It can be official, with a proper trial and all, or it can be unofficial, with the victim's family dishing out whatever sort of justice they prefer. The whole reason for a criminal justice system is to satisfy people who would otherwise take matters into their own hands. There are a heck of a lot of people who would do it, and nearly every potential victim has a family member who would insist on doing the dirty work.