I think there is at least something of a middle ground for almost-but-not-quite-public spaces and events. In this case the author is talking about airsoft games; it seems totally reasonable for the venue or organizer to enact policies, whether "no cameras allowed" or "purple helmet means don't show / blur this person".

In fully public spaces I think we're pretty much out of luck, though I do think that laser/lidar-based countermeasures should be legal.