That's right. Huge multinational corporations famously don't like money.
My suspicion is the focus is more on the first than on the last of those statistics.
If the focus was on the last we’d hopefully not see so many spurious rejections.
In some cases yes. The whole concept of 'Innovators Dilemma' is built on this fact. Squeezing an extra million here or there is a waste of Apple's time at their scale. It doesn't move the Apple revenue needle. Getting WP or some fitness app, even in aggregate to give 30% of a subset of customer subscription does nothing for Apple except hurt their brand. It probably actually costs them money from losing brand value.
Google OTOH pays Apple billions to be the default and/or first position on the search list. That's why we're unlikely to see an Apple search engine anytime soon.
And in our case adding IAP will surely make for a poor user experience. How a fitness business can serve users that sign up for an in-app purchase from anywhere in the world. A personal trainer can't help everyone. They have a specific niche and specific type of people they can and want to serve.