I'm surprised to see you downvoted here. As a maintainer of an open source project, libgit2, which is GPL licensed and used by Apple, I am rather frustrated by Apple's behavior.

The source for libgit2 itself is not present on their opensource site, though they use it in Xcode. (Git itself is present, but is sometimes out of date compared to what they're actually shipping.)

I've emailed them about this and they offered to provide me the source they used. This feels like they're trying to do the bare minimum of compliance - and making even that nonobvious (since they have an obvious distribution mechanism.)

This complaint is not a claim that they're violating our license, but it's definitely not an ideal situation, and I'm sympathetic to your frustration.