IMO, most people (regulators?) don't appreciate/understand the R&D costs associated with developing and maintaining an ecosystem like the Apple Store. The quality of the Apple Store, and development (APIs, etc.) provided to customers and app developers is extremely high quality. But there's a cost to providing an ecosystem like the Apple Store, so yeah, app developers can't expect to have the ecosystem for free just like brick and mortar stores can't expect not having to lay rent for the stores.
IMO, most people (regulators?) don't appreciate/understand the R&D costs associated with developing and maintaining an ecosystem like the Apple Store. The quality of the Apple Store, and development (APIs, etc.) provided to customers and app developers is extremely high quality. But there's a cost to providing an ecosystem like the Apple Store, so yeah, app developers can't expect to have the ecosystem for free just like brick and mortar stores can't expect not having to lay rent for the stores.
Very well put, people say 30% is high. But I say brick and mortar stores traditionally charge way more for rent than 30% of a store's income.