I'm not going to touch the issue of parents being at the bus stop...I'm a SAHM, and I've driven my kids to school every day of their lives (my oldest is now a senior)...I enjoy the extra time with them, and they seem to enjoy it too, and I'm lucky to be able to do it.
ANYWAY, regarding the unsupervised, and somewhat unruly kids at the bus stop who are putting themselves in danger, trespassing and being destructive...if it were me, I'd make a non-emergency call to my local police department, and talk to an officer about it. Perhaps an officer could observe the bus stop one morning. I bet a police officer talking to these kids about safety and not destroying other people's property would have an effect on them. Anyway, just a thought.