Android vs. iOS usage
Don't know why they discuss this when the answer is already known. Three reasons:
1) iOS dominates the tablet market where people surf longer, shop and consume more data. It was just two months ago the first mass market Nexus 7 and Nexus 10 was released. There's also data that shows when it comes to cellular data the split is 50/50 between iOS and Android. But over wifi (where tablets are used more) iOS dominates.
2) iOS has a massive installed base. Samsung Galaxy S2 which was the first phone to challenge the iPhone on its own turf did not come until last year.
3) There are Android phones on the market that literally cost $50. Those are more or less useless for surfing. Even if they are a small share of the overall number of Android devices they drag the overall statistics down. (If you think that they represent a large share of Android devices just look at who dominates the Android sales: Samsung and HTC who both are premium device makers).
John Gruber's argument of "better customers" is classic Gruber rhetoric, because that's what he wants to believe. There is no difference between a Samsung Galaxy S3 customer and an iPhone 5 customer.
Edit: there's also a popular statistic that shows how much more shopping is done on iOS than on Android. This shouldn't be so surprising given the statistics above and that iPads are premium devices and more or less require a credit card to function.
This appears to be primarily a series of unsubstantiated assertions and anecdotal observations.