The iPhones sells in the US at huge margins and is the #1 seller and profit maker for the company. All over the world the iPhone has stronger competition, not because there is a better phone out there, but because carriers are playing a different game and are offering phones and contracts at a much cheaper rate than in the US. And of course, Apple is not willing to play that game and neither are the carriers that are offering the premium phone. Thus people are less likely buying the iPhone than in the US.
Why are we in the US so gullible and are taking those expensive phones, and even worse, those ridiculous overpriced carrier plans?