Ezra Klein in the LA Times a few days ago:
Prison rape occupies a fairly odd space in our culture. It is, all at once, a cherished source of humor, a tacitly accepted form of punishment and a broadly understood human rights abuse. We pass legislation called the Prison Rape Elimination Act at the same time that we produce films meant to explore the funny side of inmate sexual brutality.
Occasionally, we even admit that prison rape is a quietly honored part of the punishment structure for criminals.
Convention dictates that no politician can afford to take on prisoners as a constituency. Politically prisoners are high risk and offer low returns. Release one inmate who relapses and a politician is immediately branded as soft on crime. The votes an elected official loses for implementing sensible prison reform aren't offset by the votes of prisoners or ex-felons since those groups are often denied the right to vote. There are good reasons for prison reform, some of which Ezra discusses, but rarely are the political obstacles to this reform openly acknowledged. Those most affected by the dysfunctional prison system are largely unable to exert the political pressure necessary to fix it. Prison rape is allowed to go on partially because of the passive acceptance Ezra notes and partially because of the political disenfranchisement of the abused.