You clearly haven't used Google Glass. With the exception of the camera, everything is inward focused. Everything you do and see and interact with glass happens with only visibility to you. Nobody else can see what you are seeing.
I have, so don't make such sweeping assumptions. I've also been around people who are using them. I find their use in my presence to be an invasion of my personal space.
I wouldn't compare it to the boombox at all.