With Debit Cards, the issue at the start was the fees were broadly the same as for Credit Cards, and did not take into account the different risk profile.
As for Apple's share - Granted, it's their platform. But they can afford to be less greedy. After all, take the likes of Warren Buffett, Bill Gales - they can't give their money away fast enough. In the case of Apple, what's all that pile of cash that has been accumulated doing? They can well afford to take a smaller cut, thereby making the total cost of ownership of the whole Apple ecosystem cheaper for their customers. Therein lies the problem. The "idiot tax" as it's referred to in these parts