Really? You've heard from developers directly and they say they want to give Apple ZERO? Doubtful. Maybe an alternative avenue for distributing their apps where they can control their costs. From a business standpoint, doesn't that seem fair?
You've probably heard no discussion about "reasonable amount" because it's none of your business. Why should you know?
Won’t an alternative store (replete with its own alternative payment methods) essentially lower Apple’s cut to zero?
To me, it’s a logical end point. People were fine with 30% many years ago, and today they are complaining of it being too high. Lower it to 20% and they may be happy for a short while but I am sure it will only be a matter of time before they start complaining again.
Lower it to 5% and you will probably still have people arguing that Apple could probably afford to run the App Store at a loss by absorbing all costs due to how much money the iphone makes.
The reason why we haven’t heard much discussion about this is because what passes for “reasonable” is going to vary from user to user. I would say that for the developer, anything higher than 0% is unreasonable, because any money that goes into Apple’s pockets is by definition money that isn’t going into their own bank account.
Who gets to decide what is fair even? Would the courts even have the expertise needed to decide what a fair cut entails?