This ridiculous idea that "it's in public so you have no expectation of privacy" is a semantic retcon, the pervasiveness of cameras is new and fundamentally changes your level of exposure in the public sphere. Overtly recording people in public is not really OK. Face-mounted, covert recording is another step too far and offensive to most people.
If you genuinely wish to understand the attitude, may I recommend doing a deep dive into the many fine articles written about this back in 2013-15, when Google failed to launch the original glasshole-wear.