I never realized that before, now that I think about it! However, I think authors often do that because it isn't the object or person itself but the metaphorical meaning of it. For example with The Silver Chair, although the object itself doesn't appear until half-way into the book, the chair itself bears deeper meaning. The chair bound Rillian, keeping him prisoner, and not allowing Narnia to have it's true heir. When he destroys it, he is releasing the bonds he had to the underworld and is going back to Narnia. The title is defining the book in a deeper sense, as the main characters in the book go and release Rillian from the Silver chair, physically, and Rillian frees himself from it, mentally.
"But even a traitor may mend. I have known one that did." - (King Edmund the Just, Horse and his Boy)
@kingedthejust Good point, I never realized this interpretation. It does makes sense.
"In your world, I have another name. You must learn to know me by it."