The findings are not really comparing two equal worlds. Apple charges an annual fee to publish which is higher than the one time Google fee. You also can publish Android apps without being part of the Google Play Market. If you assume the development costs are equal - which may not be true - the money needed to recoup your costs and start turning a profit is much lower for Android.

Many apps have a donation system as opposed to a paid license so you could turn a decent profit with donations on Android where it will take a bit more to cover the recurring expense for iOS devices.