I understand that it is typical for the book-seller (like Amazon) to get a 55% discount off of the list price of a book. So, assuming that the book sells for list price, the book-seller makes a nice 55% profit. Why is it that the entity that only sells the book makes more profit than the author, the publisher, or anyone else? Afterall, the author worked on that book for many weeks, months or years. The publisher may have spent considerable time and money in the editing and production of the book. The seller spent a few minutes making the sale. Does this sound upside down to anyone else?

I’m sure there is some crazy historical reason for this practice, but even if that reason was valid long ago, it is still valid?