If your phone was listening to you and transmitting your voice data all the time, you will notice the impact on your battery and data usage. Siri.

I agree in principle, we would probably notice, because most engineer are occasionally lazy or idiotic.

But, I can think of ways to make this happen without any battery impact. Capture in a format that doesn't need re-encoded in the moment, and wait to convert and transmit only when the phone is plugged in. Don't even clean up the data on the phone, just trickle the highlights up to the cloud.

Then in some future version of Android, wedge in a local AI layer, and call into that to pick highlights to share with advertising partners.