[crazygringo]

It has to be the same rate across app purchase and in-app transactions.

Otherwise every app will be free but charge a transaction to unlock its functionality.

[mvdtnz]

And what's the excuse for Google getting a cut of every book an e-book reader sells? Or every monthly charge from a subscription based video service like Nebula?

[crazygringo]

They already charge less for those -- 10–15% rather than 30%:

https://play.google.com/console/about/programs/mediaprogram/

But the excuse is that it's their platform and they set the rules. If you don't like it, you don't have to build a business selling there.