I'm not advocating any comforts for prisoners, so bear that in mind when you read what I post next, ok?
The fact is, prison punishment is simply a loss of liberty. Removal from society is seen as the punishment. Years ago, the sentnce would have been, say, 10 years and hard labour. Notice the 'and'. These days, you get imprisoned to take you away from society, nothing else. You can argue the rights and wrongs of that, but that's what our laws dictate as punishment.