I'm only picking things up passively but as far as I have read, it is because the App Store does not track you across OTHER COMPANIES apps and websites. If they only track you within their own Apple ecosystem, they don't need to ask for permission (same as other apps).
Facebook kept their shadow profiles to themselves, but that didn't make it any less gross. Defending Apple's data collection on the basis that "they don't share it" is like defending a guy taking creepshots of you in the bathroom because he doesn't look like the sort of person who would cause you trouble.
The sharing's not what makes it "tracking", by Apple's definition, it's collecting data on other companies' sites and apps. As in, following you around wherever you go. Tracking.
It's the difference between Wal-Mart recording you with camaras in their stores, and recording you with camaras in all stores... and at the public park, and in your home, and....
FWIW I think a whole hell of a lot more than what Apple calls "tracking" ought to simply be illegal, but they've been pretty clear about what they mean by the term, and their definition does make sense, and that is one of the worse behaviors among the spyware industry (which is basically all software, at this point, which, WTF, how did norms change so incredibly fast?)
