If I put on my naïve glasses for a moment:

Apple has a monopoly on iOS devices. There is no competition. And if somebody would built a better or freer iOS device, Apple would use the full force of the state to stop them. So, in a very narrow fashion, Apple does use their government-granted rights to coerce you to buy it's devices, if you want an iOS one.

Of course, nowadays Android devices are more than adequate replacements for many users, so most people do have the option to buy outside of the Apple world, as you suggest.