Where did you come up with these conclusions? Android has a much high market share, so they will win the downloads game by sheer volume of users. The revenue difference highlights make up of iOS vs Andriod devices and ultimately their user base. The majority of Andriod users are on sub-$200 handsets. Someone on a cheap $50-$100 Andriod smartphone from Alcatel isn't going spend $5-$10 on an advanced featured productivity app, nor are they likely to buy apps in general. They WILL download plenty of free apps, however. Nothing wrong with the people on those devices, I'm just telling it like it is.
Let's stop pretending that every Android user is using a Galaxy S6, Galaxy Note 4, HTC One, LG G3, or a Moto X.