It's not so clear cut. At least admit that a lot of thought has been given to this, none the least by Foucalt's famous essay on this topic, Discipline and Punish.

Foucalt has his critics, but it's not immediately obvious that the massive incarceration problem in some Western nations is better than public execution at the whim of monarchs. And some forms of torture, Foucalt argued, have changed from the theatrical and public to the more subdued torture of everyday lives of prison inmates.