to serve and take notice

Around Boston, business folk are very fond of backing up statements that you shouldn't do something with the threat that police will take notice. Three examples:


(private parking near Inman Square--which, incidentally, is the home of Magnolia, my new favorite Cambridge restaurant)


(laundromat near where I live)


(no parking sign spray painted on wall in theatre district, Boston; includes me with horrible red-eye)

Is it just me, or is the idea that police will take notice not exactly the scariest threat in the world? Even, maybe, does it not seem like much of a threat at all? Every time I see one of these signs I think, "And then what?"

I've never seen one of these signs in the Midwest. (Or if I have, I haven't taken notice.) Is this a Boston area thing? An East Coast thing? A cities larger than Madison thing?