They probably see it as essential for the economy. The cheap labour in prisons helps keep the US trade defecit down at an acceptable level, otherwise you'd see a lot more made in mexico stickers on your office furniture. 'Free' market capitalism demands a 'flexible' labour force (flexible meaning cheap (the real reason your southern border is so porous)), don't get more flexible than slaves
Actually it cost about $50K per prisoner a year if not more, so it is by no means cheaper labor. It's about suppressing voting rights of poor people and minorities. It's about government control for total world domination.
VOTE RON PAUL!
