So ask yourself: Why does Netflix not have this problem? They don't pay Apple a penny. Because they read the contract, decided not to violate it, and figured out how to get 100% of their revenue. While staying within the contract, and Apple doesn't mind.
Apple applies different rules to gaming apps and subscription video apps (the obviously made up a few months ago "reader" differentiation), and I can assure you, Netflix do have a problem with Apple's policy which is one of the reasons Netflix increasingly doesn't support new Apple initiatives.
It is very likely Netflix will join this suit if it thinks it gains enough momentum Apple won't be able to punish everyone.