[Nasrudith]

You might want to look at the historical status quo before prison - I highly doubt you would approve of public floggings, mutilations, and quickly carried out (from trial at least) executions. Prison requires cheap enough food or a high ransom to be viable as an institution to allow keeping them working and some means of ensuring they cannot escape or fight successfully - potentially guards as well.

It can be a historical running dark joke - "Sadly <x> still qualified as an improvement." such as slavery technically being a bit better than early human warfare ending in genocide either directly or indirectly (forced out of all territory capable of sustaining themselves).

That doesn't mean we shouldn't try to do better (ones with far better recidivism rates should be a model for one) but given the history it isn't a failing in itself - that would suggest a shift away from widespread killing and mutilating people was a mistake.