The bigger issue is whether they have completely secured this data if you do opt-in to being traced. A lot of apps try to exploit iOS and pull in data from other apps and iOS settings. Facebook is unbelievably bad about this.

I don’t like Apple’s social stance, but they are pretty strict on privacy. That’s not to say they are infallible, but the culture emphasizes the privacy of their users. They know they can charge premiums on devices because they spend so much on privacy.