"I say "American", as that's key"

Actually, America is arguably middle-of-the road, as far as this goes. Apple sells iOS devices into countries that are dramatically more censorious.

While Apple probably don't want an Apple Store in Tennessee shut down by some local sheriff on a distribution-of-porn-to-a-minor charge because of an App Store app, they also need to consider Malaysia, Singapore, India, UAE, etc. Even Australia, for that matter.

Also: App Store slander would probably be a bigger deal with regard to the UK.