Re: your examples:
She didn't call the police and make a positive ID. She didn't swear out a complaint. She didn't prevent a crime, because the miscreant had already ridden his bike through the flowers. She took vengeance on her own account.
The first sentence you quoted said she tackled someone she believed to be the ringleader, so she didn't have positive knowledge that he was. Not good enough.
The second sentence says she grabbed him after she had seen a kid ride a bike through a flowerbed, not that she had seen the boy she grabbed ride his bike through the flowers. (I'll concede, for the sake of argument, that the community has posted signs indicating that the public are to keep to designated paths or something similar, and that some misdemeanor trespassing and destruction of public property actually occurred.) So she grabbed the first one she could catch to "make an example" of him. Vengeance, not justice.
If we are to pretend to civilization, we must behave in a civilized manner. When it comes right down to it, this means that adults, however provoked, must set an example of civilized, and dogged, adherence to the rules, presenting a unified front to the punks among the kids. If the kids in general, and the punks especially, see the adults behaving like punks -- lack of self-control, disregard of public regulations and laws, acting on impulse -- then, to them, it becomes a society in which the punks are in charge.