Well, and some of them are just rather cluelessly trying to help and/or check up on somebody who might be in trouble, but they feel that local LE are the appropriate “official” channel to do the reaching out.
Illustrative example: I have also had the cops called on me once while I was standing at a bus stop. That time, it was because a disheveled-looking elderly woman with dementia had eloped (Word of the Day 
) from her care situation in the neighborhood, and apparently I fit the profile. 
The cops were embarrassed about the mistake, although I certainly didn’t give them a hard time about it (hey, however many years down the road that very well might be me), and were clearly not thrilled to be tasked with going around asking random women outdoors if they’re an eloped dementia patient.
But a lot of people nowadays do seem to think of local cops as basically neighborhood nannies: they’re expected to take the place of all interpersonal interactions between strangers. If you need to communicate with a stranger in your vicinity for any reason, whether or not you’re feeling personally frightened of them, you send the cops to do it. (That’s an exaggeration, natch, but more true than we might like to think.)