Well, Yelp pays 30% of the app price, and 30% of in-app purchases. I think the app is free, and they have no in-app purchasesApple's App Store has identical rules for everyone, and as a result some companies pay for others.
Yes 30% * $0 = $0. If Yelp had to pay thousands every month to have an app on iOS, Yelp would simply not make an iOS app and direct users to the web version which is not a great experience.
Every developer has free usage of Apple's resources and it's funded by the 30%. It's fair for everyone and it improves UX for everyone. 30% makes sense to me!