Celebrities who claim to have actually written their books without help (i.e. Trump) are few and far between. Many recognize their collaborators in the acknowledgements or on the cover. If every president, artist, or entrepreneur had to spend a year typing their manuscripts, the publishing industry would collapse.
I'm not exactly sure what your point is about "transferring copyright" -- all of my contracts state that the client takes ownership of his/her content. After all, it's their story, I'm simply transferring it from a spoken story into writing.