I found it much easier to rate an app on Google Play. You see the stars directly and when you click on one you can send it immediately.
On App Store you have to click “Reviews”, then “Write a Review”, then you see the stars, and then you should enter a title and finally your thoughts. Too many clicks and too much hassle for me.
That can be a reason why you get more and higher ratings on your Android app.
PS: Awesome article John!
I have done the same job reading ALOT of reviews. I would like to add that it's important to answer “some” of the comments as well. I dont know how many 1 stars I´ve turned to 5 just by answering and explaining how the apps are working.