That's at the heart of it - is examining a person in public with automated tools, unethical? Just saying it is, isn't a compelling argument.

The FBI can use automated tools for surveillance - which doesn't speak to ethics directly but indirectly, as we hope ethics drove those rules.

I can sit in my private store and observer people out the window all day, even take notes. That's not unethical; that's a sociological experiment or some such, and done millions of times a day.

It may be jarring or creepy to imagine an advertisement is sizing me up. Again, ethics is more than 'does it make people uncomfortable'.