The difference is that these are powered by the mains and you wouldn’t see battery drain. With a phone they’d have to give up battery life - from my understanding more than any phone currently could give up and be usable - to be constantly listening. My phone is only really on power when I’m asleep, but this would always have power and be able to listen without me knowing.

Not making accusations but I do think there’s a real difference between a microphone I’m always using and see and care about the battery drain of, and one plugged into the mains with no battery concerns.