[mruts]

The root of the problem is that we as a society can't agree on what the purpose of prison is. Is it punishment? Is it repaying a debt to society? Is it reform? Is it to prevent people from committing more crime? This is also the reason why the US justice doesn't make much sense either.

Because people have vastly different views on the matter, we are unable to construct a prison system (or justice system) that makes any sense.