One of the minor themes is old people obsessively, aggressively filming everything in public.

Note how well "robots.txt" works: the problem is bad actors tend not to follow "social convention" rules like that. The people that do adhere to such rules are probably not going to be the worrisome agents, anyway.

Furthermore; the laws are already ahead of you: if a store's surveillance video is requested by a court, and it has blocked out the people wearing "don't see me" codes; ... who does the court hold has destroyed evidence? Store owner that turned the feature on? Vendor that enabled it? Person who wore a mask with the activating code?