Here's a radical idea: invest in mental health, food security & education, and community programs to directly combat the source of the gangs and bad behavior, rather than try to control people's behavior.
That is the distinction you've seemed to miss here.
Controlling others' behavior is ineffective at best. It's treating symptoms with pain killers while ignoring the source of the problem. It's weak leadership, and, it gives broken people the ability to manipulate the system to hurt others.