Lots more to explore looking at this, but one point stands out. I sometimes feel like Cato saying this over and over, but the iPhone is more expensive than most of the phones on the market, and this shapes the kind of people who buy it.

Also, it's worth pointing out that the site that made these is laying iPhone on top of Android rather than blending them. There's Android in the central/rich areas too - though often less. But iPhone is concentrated in those areas.