Just because an OS has a "majority market share" doesn't make it a suitable market. Elegant, minimal premium apps like Clear have done well on the iOS app store, but it's hard to imagine a $5 calculator app getting much interest on Android.
"the App Store generated 2.3x more revenues than Google Play."
http://www.theguardian.com/technology/2013/aug/01/android-ap...
A calculator app is an outlier; it is not an average app. It's also an outlier with real utility --- so it's something people are more likely to pay for.