Oh its definitely rent seeking. They are trying to eek out more money from customers without adding additional value. Headphone jacks, no SD card for storage, no charger blocks, no ability to add music to your device without a windows or Mac computer, etc.... We can go on and on and won't agree so we do not need to continue to discuss this. No they are not forcing you, but they are absolutely rent seeking. (everyone is these days).
No push notifications (this is unsurprising, Apple runs the push notification servers, and those cost money). I don't see anything about linking against third party libraries.
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More to the point, you keep using this term "rent seeking" to describe Apple selling optional services. Nobody is forcing an iPhone owner to pay Apple for services. Rent seeking implies once you have the thing, you have to pay rent on it. That's just not true for iPhones.