> I am sorry for being so flippant and unreasonable expecting to buy a digital book using my smartphone in 2023.
I feel that you are being unreasonable: you willingly bought into a closed ecosystem, and now you're mad that other people are not part of that ecosystem.
You should be mad. But not at Amazon - at Apple - that wants to charge every 3rd party book store 30% to sell a book on an your smartphone, but not it's own book store.
Microsoft was fined billions of dollars and went through years of litigation over something much less egregious.
Apple's (And Google's) digital tax is what you should be mad at.
If your device of choice is one that you don't really control but that instead is just a pile of limitations on top of constraints, I'm quite amazed by your expectation.