I'm of the opinion that leaders are made not born and in particularly made on the battlefield. This sleuth of new officers that came out fresh out of West Point has had a hard time keeping troops on point, not so much now as in the beginning of the war. When your subordinates are accustomed to gang life and to a particular ethnic group you're are going to have a problem with discipline. On the Ethnic side I know that they didn't like taking orders from a whitebread gringo, and when they are in a gang their rules supersede those of the military. For as long as they don't rock the boat to much, they get away with much and it gives them confidence that they have control and officers don't have many punitive resources as their main job it's to keep their unit together.
It's a few cases where officers play by military rules when the rest are playing by prison rules and of course there is the most heinous case where the officers are the perpetrators.
Because the military turns a blind eye to many of these events and tried to keep them under wraps, the few good men are stuck with no justice other than the one they make.