With a truly hidden camera, you would never know. So you're freaking out over someone who might be able to record you, ignoring the fact that everyone could be recording you without you knowing it.
Either you're wilfully ignoring the point I'm making, or you've missed it completely.
I get that I might never know if or when I'm being monitored by some device, but that in no way justifies explicitly recording someone without their permission.
I get the point you're making. But if you're in a public place in the US or UK, you have given your consent to be recorded. The difference between Glass and smaller, less conspicuous recording devices is that with Glass at least you know there's the possibility of being recorded by that person (same way with cell phones). If someone really wanted to record you without your permission, there are cheaper and sneakier ways to do it. Also, it's not that hard to pull out a phone and pretend to text while actually recording video. No one would ever know.
So the idea that people wearing Glass are assholes is a ridiculous notion because there are already numerous ways to record someone without explicit approval, you already have the right to record anyone in a public place even without explicit permission, and it's already possible (and already happens) with existing smartphones. So if you're getting mad at Glass wearers for something that people are already doing, you're the asshole. The only difference between Glass and other technology is that Glass is newer and less common. That's it.
The photography of an individual can constitute harassment even in a public place - there is no implied consent involved. Even if it were, as you implied, perfectly legal in all cases then this in no way makes the act ethical. This is especially true when concerning a new technology which makes it trivially easy to perform. I'd expect if Glass, or some descendant of it, becomes more ubiquitous, then social guideline and laws would eventually prohibit it's use in certain situations. Would you, for example, be happy with someone recording you in a public restroom?
You're also repeatedly missing the argument I've already made twice in this thread with your second paragraph,
Filming someone is rude. What are you going to do about it? Ban smartphones? It's trivially easy to pretend to use your phone while secretly recording. Ban DSLRs? I could pretend to be taking static pictures while actually running a video. Ban video cameras? They might look like they're idle, but maybe they're recording with the "recording" light turned off. Ban surveillance cameras? Hell, anyone can hang one of them on a building, and who knows where the video will end up?
I'm not missing the argument. You're just not making an argument worth refuting. "Oh no, someone has a device capable of recording me" so fucking what? Welcome to 1975, you can buy recording devices at a dollar store. No one looks twice when there's a CCTV camera or a smartphone out in public.
You hate Glass because it's unusual, not because it's capable of recording you.
