We all know prisons didn't always exist, but they exist now, and they exist for a reason. Have you ever considered that the reason prisons didn't exist in the past and they do now is because the material conditions of the past were different than they are now, and thus different systems that weren't needed in the past are now required? Less people made up communities in the past, so prisons weren't really required to handle rule breakers, unlike in our modern large communities.