He is making an entirely justified complaint that Amazon charges unreasonable fees. The idea that any and all corporate behavior is fine simply because "it says so in the contract" is ridiculous.

You aren't actually paying attention to what the author wrote - he even specifically talked about how Amazon's Kindle platform provides a good experience for readers and has accounted for the majority of his sales. His post doesn't display any ignorance of the points you are making - instead, he acknowledges them but makes the entirely valid point that charging several dollars for a "delivery fee" of a digital book is OBVIOUS BS!

There is a huge disconnect between the attitude of "any price that people will pay is a fair price" and the fact that economic systems require that parties engage in transactions in good faith. To me, it seems blatantly obvious that Amazon is engaging in the bad-faith practice of trying to conceal the true costs of their service by loading a lot of the price into a "delivery charge" that is absurd.

This kind of thing is a very old game in business, but that doesn't make it ok. Just because something is common and legal doesn't make it appropriate. A large amount of standard business practices are deliberate, but legal, rip-offs - and calling a rip-off a rip-off is a good thing.