see, this is the thing about glass; There's a whole lot of useful stuff you can do with a HUD that doesn't involve a camera, and wearing a HUD would be a hell of a lot more socially acceptable if people didn't assume they always came with cameras.
Or hell, just a 'the camera is on' indicator. a red light, or a bit of plastic you can slide over the lens or something. (I mean, clearly, both of these things can be faked, but there are a thousand other ways to conceal a camera on your person, if you are being deceitful. The important bit is to make a clear way of setting the social expectation that the camera is on/off.) Personally, I'd favor some kind of physical lens block, as it guarantees my privacy (during the times I physically block the camera) even if the firmware is compromised.
Or hell, just a 'the camera is on' indicator. a red light, or a bit of plastic you can slide over the lens or something. (I mean, clearly, both of these things can be faked, but there are a thousand other ways to conceal a camera on your person, if you are being deceitful. The important bit is to make a clear way of setting the social expectation that the camera is on/off.) Personally, I'd favor some kind of physical lens block, as it guarantees my privacy (during the times I physically block the camera) even if the firmware is compromised.