b) Apple charges 15% for developers earning less than $1m a year.
I don't understand how even as low as 15% of all the apps revenue can be less than $1m a year though and, if it is, why would Apple even bother collecting it.
> Apple charges 15% for developers earning less than $1m a year.
As this:
> Apple charges 15% for developers, earning less than $1m a year.
When it actually means this:
> Apple charges 15% to developers who earn less than $1m a year (and still charge 30% to developers who earn more than that).