While I don't agree with these sorts of industry practices and believe the US needs a universal data privacy law, I don't see how matching up some relatively impersonal metadata could be considered worse than directly listening in to private conversations.

The advertiser trying to sell my friend appliances didn't really get a lot right about them. They're a renter and the advertiser thought they’d like to buy a major kitchen appliance just because we were in the same location.

If they were able to listen in to our conversations they wouldn't have sent them an advertisement at all.

Now this could be a fun adversarial exercise, with more interesting products of course.