> Why aren't Apple's apps themselves also having to ask for permission? I personally do not trust Apple one bit, just as I do not trust Facebook. So why is it so much harder to disable Apple's tracking, compared to Facebook's?

They do ask, either on every OS install or upgrade (things like Siri) or first use (non-core apps). If you look at the various privacy settings, Apple’s own apps are listed and you have the same controls to block or limit the data they can access.