How true this is. As someone who has worked on a couple of books just like this, I can say even I didn't understand why the author agreed to this sort of deal. Don't get me wrong—I was offering her the very most I could without sending the book into negative profit. Some books truly shave much closer to the bone than others. If she hadn't agreed to that deal, we would have had to abandon the book—that was simply the most we could offer. But still.
I am getting ready to sign a contract for a children's nf book with a small advance that will be used, per the publisher's unnegotiable demand, almost entirely to find and purchase photographs to illustrate the book. How depressing is that? Still, according to the publisher's statistics, books similar to mine do earn substantially after several years. My co-author and I are calling our upcoming year of basically no pay and a whole lot of work "an investment" in the future, but I can't help feel a bit downtrodden.
Oh, I hear you on the nonfiction stuff. Another writer told me that if I sold my nonfiction book that I should use the advance to pay for a trip to do more research. Cripes, I need the advance to pay for a trip to the grocery store.
Good luck with your project!