Prisons weren't created to rehabilitate people. Really, it's simple economics.
Just like in the economy, in the legal realm there are behaviors you want to encourage and behaviors you do not want to encourage. Economically, you want to encourage free trade to increase competitiveness, so you eliminate tariffs. You don't want corporate shareholders to save all of their profits, so you give them tax breaks when they invest money into improving production.
Legally, you don't want people to behave outside of the law. In order to deter them from doing so, you create costs (punishments) that are large enough to make them wary of doing so. Prison, taking time from your life and removing the freedom to live within your desired conditions, is that cost. If we make prison life too "humane" and like everyday life for law-abiding citizens, it removes the deterrence factor.
Just like in the economy, in the legal realm there are behaviors you want to encourage and behaviors you do not want to encourage. Economically, you want to encourage free trade to increase competitiveness, so you eliminate tariffs. You don't want corporate shareholders to save all of their profits, so you give them tax breaks when they invest money into improving production.
Legally, you don't want people to behave outside of the law. In order to deter them from doing so, you create costs (punishments) that are large enough to make them wary of doing so. Prison, taking time from your life and removing the freedom to live within your desired conditions, is that cost. If we make prison life too "humane" and like everyday life for law-abiding citizens, it removes the deterrence factor.
That's why people living in poor conditions are more likely to commit crimes--they have less to lose by going to prison than someone with a nice house in an upscale neighborhood.