Why?
I'm not saying anything that the sales numbers don't already say (app sales, subscriptions, click through rates, anything): Android users just don't buy as much stuff with their phones, it doesn't mean they're poor it just means they don't like to click pay through the hamster's wheel of mobile purchases as much as iOS users.
My point is if the average Android user were even half as likely to buy then the numbers would be about the same plausibly, they wouldn't be half the revenue. I suspect if you're a small shop focused on apps for the top end of phones you just don't have time for all this.