Yes it's true, iPhone are popular, but it's a US-centric answer, because most of the rest of the world runs Android (Android has a 70.69% market share worldwide).
So Google has a really valid plan there.
Google claims their target is the "next billion people".
Also iPhones are very expensive, just relatively less expensive in the US (due to wages, low taxes, less intermediaries, etc).
Even a poor US citizen is often some sort of rich citizen in other parts of the world.
Of course, there are exceptions, for example, Kim Jong Un uses iPhone and MacBook Pro.
You know what they say about making up statistics...