The question wasn't "which ML use cases are potentially good", it was "which ML use cases are seen as predatory by users". So it doesn't matter that face detection has the possibility to be good, it's currently bad
Bad, but not predatory. For example most speech recognition systems I tried often produce hilarious results with my accent, but I don't feel the tech is out to get me, it is just less than useless.
On the other hand something like ad-tech feels more dangerous the better it works, to the point that I employ active countermeasures.
