Netflix reportedly had special terms for years before that policy change for everyone else. I don’t think they were the only ones.
I think Apple just did that because it was becoming clear that what they were saying wasn’t true/they were getting political pressure about charging 30% no matter what.
I don’t remember the exact timing on the change so my guess as to the cause may be wrong.
Supposedly, the 15%-after-first-year rule for subscriptions that they instituted was because they were trying to entice Netflix to continue to take in-app payment for subscriptions. Rather than a sweetheart deal, they rolled it out as a platform change.
There are areas which I think are more questionable, such as their Apple TV partnerships with Amazon and a few others.