I just finished the charming short memoir from actor Cary Elwes, As You Wish, about his experiences while filming The Princess Bride. The voice sounds very much like Elwes, but the cover clearly says "with Joe Leyden." Which says to me "ghostwriter."
It's reasonably common for someone who's not a writer to get a ghostwriter to help with a memoir, but Elwes is also a playwright, so it's not like he can't assemble a sentence.
So my general question is this: how much work does a ghostwriter typically do in a nonfiction piece, such as a memoir?
I realize that the answer can vary from "everything and the client waves at it" to "act as more of a heavy copyeditor," but I'm curious to know if there's an industry standard or expectation. I also noted What to include in agreement with a Ghost Writer. . . but that's more of a contract checklist question, not a "here's what typically occurs" question.