Yet US has one of the highest reoffending rates at 80%. Norway has lowest at 20%, rather than "punish" they rehabilitate. With such vast numbers reoffending it's arguably a national security issue. Taking up the mantle to push prison reform now you are free would be a VERY worthy cause. Ive no idea where libertarian party is on that issue, but inmates also have rights to liberty.
Discussion
There is an overwhelming body of research to the contrary. Just find countries with lower reoffending rates and compare/contrast their prison systems.
Don’t think Americans can be treated the same way as others. Their culture is unique
They're mostly broken humans, who need fixing. Its no benefit to the inmate or society as a whole the punitive approach. Having freedom of movement restricted is punishment enough, rest should be fixing them so they don't cause further harm when released.