People are most afraid of cameras, somehow.

The concern is valid, but microphones are far worse. They're simpler, smaller, extremely sensitive to sound and an order of magnitude cheaper, both the mic itself as well as any spying with it.

It is possible to record voice using few bytes, to send later. It's further possible to transcribe cheaply into text, and analyze said text.

And mics are already everywhere, including in devices that do not need them, as well as speakers that can be rewired by software to act as microphones.