[keanebean86]

Not a study but I've heard explanations that big companies have so much data their models are just that good. For instance they know who you're friends with, both your search histories, and location data. Knowing you friend searched for lawnmowers recently and now y'all are physically close it's possible that brand was discussed.

Although I wouldn't be shocked at all if mics were being used. I just feel like that would have been leaked by someone by now.

[clairity]

no, they have so much data because their models are so bad. the vast data is used to give the illusion of good models by sheer volume, so little random matches are made more likely. that’s why google and the like want to hoover up our data, they’re desperate to keep the gravy train rolling long enough to create the good models and keep it going some more.