Criminal psychology question... Why are certain types of inmates statistically more likely ?

Why do certain types of inmates recieve psychiatric or psycological treatment? In particular, I am curious about criminals that commit a violent crime and their victim is a 'child' -under 18. These type of offenders are much more likely to recieve treatment than someone that commits a crime against an adult - at least according to the dep. of justice. It did not seem to be specific for just ' offenders', but murders, batterers, robbers, etc. were all more likely to recieve treatment. Is there a real problem with theses types of offenders, while people who commit crimes against adults - not so much a psychological issue - or are these types of criminals at a point where most are beyond the point of that type of help?