All the towns I live around have them. They were almost never enforced on us. We loitered, we would "drag main", run up and down the street like idiots. All of us at the time 15-16. Never had any trouble with cops.
This one city we would go to though, had a lot of "hangouts" 2-3 big ones in town, (parking lots) kids would emass 100 at a time. After a few fights/drugs/noise complaints. They started cracking down. Now, once in a while they will get some greif. But most hang in groups 15 or less, no prob.
I always figured more politics than anything.
IMO, probably won't do any good anyway.