The purpose of prisons is the same as that of any other large expenditure that doesn't go directly to the poor, in an inverted totalitarian state like USA. The

The purpose of prisons is the same as that of any other large expenditure that doesn't go directly to the poor, in an inverted totalitarian state like USA. The purpose is to transfer public resources to private hands. That process is what drives every decision in a simulated democracy like the one to which we are subject.