Actually, I'm quite sure that's what they do.
My brother's in a Level 1 & 2 facility which does not house violent criminals; they're held in Level 3 or 4.
His letters have given me a keen insight into prison life, from an inmate's perspective, anyway. The only write up he's ever received is for smoking a cigarette. Seems tobacoo is no longer allowed.
If there's any good news in his whole life it is the possibility that this, his latest and most extended stay will be enough to prompt or force the changes needed to keep him from going back.
Only time will tell.