The separation of "service fee" and "delivery fee" is disingenuous, you are basically paying amazon 50% for the use of the marketplace. If you think it's an unfair price, don't put your book in the marketplace. If you think it's fair but deceptive, say so, don't pretend like it's deceptive and unfair at the same time.

Complaining about a 50% margin for Amazon when they have basically created the entire ecosystem for ebooks feels a bit like complaining about the large markups on pharmaceuticals to make up for the millions are poured into R&D.