As one of the glass explorers (who still has and uses my explorer edition from time to time), this is something that I never understood. The entire prism would light up if the camera was in use (it's easy to see when the display is on). And you either have to use voice commands or would have to touch the device to take a picture, both of which are fairly obvious. It's much easier to take a discrete photo or video with a cell phone.
But I suppose this is another case omitting one or two facts to completely change the narrative.