It has been pointed out else where in the thread that they do have mics in them. It is possible that Nielsen is only looking for audio from TVs and Phones, but Google also wants general audio for speech recognition. But I'm not sure.

i stand corrected. thank you.

But they could have!

See what I did there? It seems like confusing what a company could have done with what they did is a common rhetorical move these days.