I find it fascinating that people actually make a living with their speaking voices (as opposed to singing, for example). Some people make a very good living.
The reason I find it fascinating is that if we took a random sampling of people walking down Ocean Avenue in Santa Monica and recorded them reading a passage, maybe 10% of the voices would sound pretty decent and maybe 10% of those would sound really good. Why then, would a production outfit pay lots of cash to one person when any of thousands could do the same thing, and for a fraction of the money?
Maybe it's that people have become accustomed to a particular voice, in much the same way that people know that a Big Mac will taste the same in any Mcdonalds they see, no matter where in the world they are.