I can assure you I could buy a whole fleet of Google Glass if I wanted to. The class argument is laughable.
Also, unlike you, I've actually tried Google Glass and I can say that the only worthwhile feature was the ability to record video by taping the side of it. The very small display (it's like 8 lines max, maybe 5 words per line) and constant looking up and to the right do not make for a good user experience for any real information, imho.
The barrier is getting fired from your job.
So if I walk up to you and point my cell phone camera in your face - No problem? I think you'd get annoyed rather quickly.
Also, let's be honest, the security camera argument is a false argument, since we all know how crappy the footage from security cameras are and that there are more controls over the purpose and use of that footage.
With Glass you may become part of some weirdo's "art project" or have your image stored with Google in perpetuity for them to eventually add to their facial recognition database and who knows what else.
How often do you listen to your friends recommendations right now? How often are they right for you?
You can be friends with a lot of people, and have different tastes in all kinds of things: music, food, movies, doctors, cars, clothing,
The only perfect science is hind-sight.