But they make it very clear that the iTunes store is the only authorized/approved means of doing things on the device, and try to make it illegal to do otherwise (although the Library of Congress put a temporary stop to that agenda). And while they don't go after the jailbreakers, they do try to diminish their experience with things like the iBooks jailbreak test.

When you combine this behavior and stance with the "charging through the iTunes store" policy, it becomes effectively a mostly successful attempt to charge for doingsomething with the device. The Apple Tax in isolation, while disturbing, isn't intolerable. It's when you combine it with their other policies surrounding the platform that the real problem arises.