Some of these are "duh.." I get why they ban books about revolution and explosives, but why the hell would you ban completely benign art books and the like is beyond me.

It might be due to their size and dimensions. Either used as weapons or as a means of hiding contraband.

This is true enough. In college, I participated in a group/class/club that tutored prisoners. My co-directors pulled some pretty impressive guest speakers for our regular classroom sessions, including the #2 guy in California prison systems. Faced with a mass of earnest, fresh-educated queries about why he supports policies that seem to promote recidivism etc, given actual rigorous studies, his reply was typical for the industry: I know what I know, yadda-yadda, you people are idealistic and naive, yadda-yadda, I'm not basing decisions on what a bunch of pencil-necks write in their little reports, yadda-yadda... standard smugly ignorant, condescendingly authoritarian cop mentality.

Street Cops >>> Prison Guards