For a financial assignment, on which my byline would run, I would receive $50 for the minimum of 400 words. Of course, more would be required to satisfy the editor. Financial topics are complex. Before I submitted copy I would have to provide three possible subjects, each pitched in several sentences. Yes, details are needed. From one of those three, one assignment would be selected. Each assignment would demand three distinct pitches. Okay.
But there's more. There would be a first draft submitted. That would be edited, with recommendations for the second draft.
All that adds up to hours and hours of work. Just consider the hours consumed by researching, continuously, three subjects to pitch about. To my calculations, I would earn way less than minimum wage.
Ghostwriting, however, is a different story. For about 700 words I earn $150. I only have to pitch one topic. If that isn't accepted, the editor nicely asks me to come up with another. Then I submit the draft. Often that's the end of the line on that piece. The editor might fiddle with in-house changes. If I'm in the zone I make more than $50 an hour.
Writers have to make their own decisions about whether they want to do bylined work for peanuts and frequently great angst or ghostwriting for what seems to be a much better deal.