I may be wrong as I don't have the rules under the hand but iirc Apple's rules state that the in-app purchases prices must be set as to not push users to go pay outside the app. So raising your price may result in a takedown of your app, meaning you have to eat the 30% if you want to stay on the store.
I think if the fees were split out people would lose their minds on more expensive apps because they'd recognize it isn't good value. Ex:
Hey: $70 / year
App Store Fee: $30 / year
Also, did Hey get the prices wrong or are they talking about keeping the prices the same and eating the 30%? If they want $99 in their pocket, they need to charge ~43% more. Assuming Apple takes 30% of the sale price:
- 99 * 1.43 = $141.57
- 141.57 * .3 = $42.47 for Apple
- 141.57 * .7 = $99.10 for Hey
So by taking 30% of revenue, it increases prices by 43% because if someone is taking 30% of your revenue, you need to increase your prices by 43% to break even.