It is perhaps safe to say that in the vast majority of prison systems, there is a segment of the population willing to collaborate with the guards for better treatment, food, privileges, etc. It is equally not a long shot to think that collaborators in the Japanese POW camps, especially when you consider the brutality with which they treated their prisoners. When you have been starved to 90 lbs, served rice gruel and unripe vegetables which caused severe diarrhea, beaten until near death, and treated as something less than human and more as an object to pour contempt on, the conditions are ripe for collaboration.