It is not an odd complaint. It's a very reasonable complaint. And you appear to be the one unfamiliar with Apple products.
No, Kindle books cannot be purchased on iOS in any of the Amazon apps. They can only be purchased in Safari, because Apple blocks the in-app purchases. Apple wants you to buy from iBooks (or they want to take a slice of Amazon's profits, which Amazon's never gonna allow). Therefore, customers cannot buy Kindle books on iOS apps. This isn't up for debate, people! Stop lying and saying that you can buy Kindle books on the iOS apps. You can't!
And no, Google Maps cannot be the default Maps app on iOS. Whether you use it or not is irrelevant to the fact that it cannot be set as the default app. Yes, I use it too. But I'd love for it to be the default. This is not currently possible.
Guys, if you're real Apple fans, you can't just defend the dumb stuff that they do! I love Apple products! But I'm not going to pretend like they don't make it difficult for us consumers to use their competitors' services. They do. It's a very consumer-hostile behavior, and we have to call them out for it!