Like a person said already he sold something for 4000 dollars, and the total fees taked from those were 25% soo those websites had stoled those person, but in the end its about trust and people do trust into those two companies, and them take advantages of the reputation they have.
Right about that its all about the trust and due to that they can abuse their power over people to ask such ridiculous fee's pretty insane if you are asking me.