When you live in a civilized society, you have to play by society's rules (laws). You choose to violate those rules, you don't get to live in polite society anymore. Prison, with food and beds and other accommodations provided at the taxpayer's expense, is better than exiling them from society, is it not?

Now I'll agree that some people shouldn't be in there in the first place (possession of marijuana, multiple outstanding traffic tickets, whatever), but for people that made repeated bad choices and inflicted harm on others... Yeah, they don't get porn, books, and other niceties anymore. The most vile offenders should be lucky to even get to live in a prison in the US, which has much higher standards than most of the world. So what if they have no porn?