Prisons. Why are we paying these people's room and board? They should be at work as part of society. The original idea was educate and rehabilitate these people, with the thought that spending time behind bars with plenty of idle time on their hands would give them time to think things over. Perhaps this process could be improved with some basic additions. Force feed them a basic education. Over and over again if needed. Language skills. How to clearly speak english. How to be polite. Job skills. History. How to cook. How to be a responsible part of society. How to avoid the behavior that got them in trouble to begin with. Require straight A results on all tests before releasing them.
Many times it seems that instead prison is used as a punishment for crime. If punishment is all you are looking for, why not try some less expensive approaches? Public flogging would be a good deterrent. As far as it being cruel and unusual, it is likely a lot less cruel than sending someone to age several years at our expense.