Yeah, listening/matching for specific songs or words is trivial locally. It has been done commercially since the early 2000s (for ASCAP) on mobile phones, when they were dumb bricks. The idea that every single company is following some righteous non-profit seeking stance, is sort of laughable. Maybe FAANG have decided it's not worth it (they have other ways), but that doesn't mean they couldn't or other apps don't.