He makes an interesting point that most guards and most prisoners just want the time to pass without incident. Thus, the prisoners and the guards are often working together against disruptive forces. He put this insight to use during a prison riot—instead of sending in SWAT with teargas, assume that many of the "rioters" don't especially want to be rioting. Instead of sending in SWAT, send in some guards the prisoners know and trust(!) to strike a deal. It doesn't match what you see in the movies, but it's not surprising to hear that movies don't try to get this right.