I just hope that Apple would be allowed to say that if you are going to use outside payment providers, you must allow paying through Apple and the outside price can be no lower than 30% (or whatever Apple's cut is).
I don't spend a lot through Apple each year. Maybe $200. If I'm paying 30% more than I would otherwise that means it's costing me something like sixteen cents per day and I'm okay with that.
When I was younger, I used to focus a lot more on price. When Zappos came around it clicked for me that paying more can be smart if the service you get is better. I'll pay $0.16 every day if it means a few times per year I avoid a lot of bullshit.
Setting it worse opens up effectively a "soft disable" like Apple price at $1000 and their price at $1.
If they for some reason decided to charge $1 through Apple and $1000 through their own that poor decision is no skin off Apple's nose.
Most sellers on the App Store are now paying 15%, if anything at all. Most apps I’ve seen are using ads to bypass paying anything to Apple. Some of them support IAP to remove ads. But that’s just an option.