the jails in the USA are overfilled. it's not proper to put a person in jail and not let him do anything with his life while he wastes away for months or years. besides, after the person completes his sentence he does not become a better person because of the prison. on the contrary, it can make him worse. jails should only be for people who are too dangerous to be with others and cannot be put to death for their crimes at the moment for whatever reason.
otherwise penalties should be instituted like paying fines, damages, paying for financial support for the victim if he can no longer make as much money etc.
see link: cost of locking up americans