[mikeash]

Yes, it is that much of a stretch. Apple temporarily gave Uber that special permission in order to make their Watch app work better for their users. It’s extremely unlikely that Apple would give Facebook special permission in order to spy on users to no benefit to the people who actually pay Apple money. And somehow it’s gone unnoticed all this time.

[mikeash]

I didn't realize it when I wrote the above, but this makes my case much stronger: these special entitlements are listed as part of the app. It's far from obvious to the end user, but people who know how to look at them can do so. Either nobody knowledgeable has ever looked at Facebook's entitlements, or it doesn't have one that would let them do this.