>That's what "siri", "hey google", "alexa" etc are all doing 24 hours a day.
You might have just convinced me that the “phone is listening” is total bunk, because these dedicated devices are just so bad at recognizing the very specific, short, phrases when explicitly directed at them that I can’t imagine they are listening for much more. Listening to my in-laws try to activate their Alexa and Google Homes is something the CIA might consider for their next torture method.
You expect 95% accuracy matching activation phrases. You don't need that for ads. It only needs to work some of the time for some of the people, especially if it makes $/click.