Earlier quoted context omitted.
Which is odd... Users of the Play store and App store are a disjoint set. Very few users will switch from Android to iOS or back because in-app purchases are cheaper. Developers are generally forced to support both stores. There wouldn't seem to be any strong reason for both stores to pick identical fee structures - they aren't really in competition.
Users might not change phones but android users might have different behaviour to ios users in terms of how likely they are to spend. Which perhaps skews the developers towards starting on one platform or the other. But generally yes I agree that it can't be all that big a difference.
If those facts mean I’m counted as an iOS user once and Android user twice, the iOS me spends a lot more in the Apple App Store than the two Android mes put together.