They say they don't, we can't know if it's true or not.
The only thing we can do is vote with our wallet if we see that they have lied all the way.
This will only lead us to Russel's teapot [0].
BTW, their current privacy policy is at [1].
and i doubt mean a non biding privacy policy. heck metabook and google both always had one saying the same thing
And you cannot really confirm the above use case very well. What if it is so sophisticated that it knows when it is being monitored, or it is so random or well hidden, that it might take years to spot.
We are just doomed.