Police interact with with troubled adults and kids all the time - when they become aware of situations where these people are in trouble and have troubled families, they can and should make referrals - for example they might arrest a teenager and discover that other children in the family do not have proper parental supervision, so thye could rfer that discovery to the child protective services who could investigate and take action.
Problems police face doing this is it take away from there time and energy fighting crime in the streets, and tends to turn them into social workers.
Police street justice is more efficient but arguably less effective:
1. Our laws and constitution are there to provide "due process" and fairness to anyone accused of, or thought to be involved, in criminal activities - allowing "Street police justice" is like the wild-west; cops beating up people?!?
2.What hapens if they harm the wrong person?
3. Or the person they beating up didn't do anything - the person who told the cops was lying?
4. Processing juveniles through court system takes longer and there is more time and distance between the offense and the punishment, and therefor perhaps the punishment has less affect - but a civilized society that honors the rule of law can do it no other way!
All the best,