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.
UPDATE: don't conflate stalking with observation. These are not the same. You can observe, but you cannot intimidate.