I have successfully argued this for at least a certain class of devices. Namely, it practically can't happen _for small devices_. e.g., a TV remote with a voice feature activated by a button simply won't have enough _power_ to constantly be listening, uploading, or processing.
Harder to convince folks that _nothing_ does this, but takes an edge off their more paranoid tendencies.
I personally don't believe any argument that says it's not feasible.
Transcribing all spoken text and sending it home, sure, not feasible.
What if we have 256 keywords, or 65536 keywords, maybe preconfigured for particular products or product classes. Some basic linear predictive coding mechanism ( you know, what powered those '80s chips Stephen Hawking style, speak and spell, etc) - very very low computational overhead. When the word is triggered, queue a message back home at the next reasonable opportunity - user id, timestamp, word. It will only take a couple bytes. It can be slipped in anywhere and obfuscated by any means by nature of being so small, data-wise, even as a watermark of some sort. By using a timestamp and waiting until the next opportunity, maybe minutes, hours, or days away, no time correlation detection is possible either.
People say big tech is ethical, fine. Maybe some ad company is sponsoring some free app or game for the phone, and slipping this in there. Now the developer can pay their rent and food costs. Maybe the ad company is then selling that data back to big tech who washes their hands of any wrongdoing. Maybe it's all legal because the fine print of the EULA allows for this.
Seems to me though this can be figured out empirically, just have a voice play something like "need to buy adult diapers" or "new tires" etc next to a device, enumerate every device, look for ads on whatever very specific topic, minding along the way to tell nobody and never enter it in any internet-connected keyboard.
For sure! I mean, my Google pixel has "Now Playing" which is able to passively listen to the microphone for songs it knows, and displays them on the oled lock screen.
So, we already know that it is
A. completely feasible for a smartphone to do this.
B. At least a subset of smartphones have always-on microphones.
Maybe not a remote control... But why would you put it in a remote anyways when everyone has a phone?
I'm not sure I believe strongly either way, but after a few drinks I often convince myself it has to be happening due to the prior proof that it's possible, and the fact that if I were at the right place in one of theses companies, I'd do it just to prove that I can, and do it in a way such that the least amount of people internally would know about it.
But that may just be the conspiracy theorist in me.
Harder to convince folks that _nothing_ does this, but takes an edge off their more paranoid tendencies.