Why do people consistently and falsely believe that they have privacy in public settings? You are literally out in public. If you don't want your behavior in public to be observed, then either don't behave in such a way that you wouldn't want observed, or stay home.
UPDATE: don't conflate stalking with observation. These are not the same. You can observe, but you cannot intimidate.
So you'd be cool with us crowdsourcing a film crew to follow you and your family around in public at all times?
Would you mind if I parked near your house, such that every morning, when you drove past, I could follow you. To work, to the store, to the gym, you know, wherever.
Then on the way home I'll park where I left off. If anyone asks me I'll them everything I know about you. It's "public" information after all.
Every entrance to my neighborhood has a Flock camera from my local police department. Tracking the exact time I enter and leave my home is at the very least right at this line you’re trying to draw.