“They don’t have the right to read a book out loud,” said Paul Aiken, executive director of the Authors Guild. “That’s an audio right, which is derivative under copyright law.” — New Kindle Audio Feature Causes a Stir
Yeah. It’s like saying “You can’t sing that Beatles song”.
We don’t pay for the individual letters or words in the book, but rather for the whole content, the idea and the story. Words spoken out loud are not derivate work of the same words in writing.