I really do think you may perhaps have misunderstood what was being said. I wonder if perhaps they were talking about granting rights, and you took that as meaning transferring copyright? I've had close contacts in the publishing world for a very, very long time (in the dim and distant days of my youth I used to write physics textbooks
), and in all honesty, this just doesn't happen. Authors sign a contract with a publisher granting them the (generally exclusive) right to publish a book. They do not transfer the copyright to the publisher.