Hm. I'm not as convinced as @simon that phones aren't spying on users through their microphone inputs, but at minimum I definitely think that the companies trivially *could*. https://lobste.rs/s/zkboyo/i_still_don_t_think_companies_serve_you_ads#c_82n0i8
Also having had enough conversations with @profdiggity about the horrors of spying on phones their research lab has uncovered I definitely think this kind of thing is highly possible.