alt Hacker News>> what you're saying is "I like the knives because I can cut things" it just happens the "things" in this case are (mostly) your vegetables.
Again, I'm not saying this out of some bad faith, I just think this argument doesn't work the way you think it does. We actually have no data as to what its most commonly used for, apart from the headlines. Anecdotally, all my friends who have them use it for the exact same reason I do.
Good analogy. If there was a tool that could do everything a knife can do without being able to cut people, knives wouldn't be nearly as common and anyone who insisted on carrying one in public would be suspect. "I need it to cut vegetables," would not be a reasonable excuse, because there's an alternative.
There is an alternative to your stealthy camera glasses, which you are aware of, and your admitted use case for them is filming people who are unaware that you are filming. Yet you can't imagine other people use them for the same purpose? I'm trying to assume good faith but you're not making it easy.