'Those customers are both on the author side and the editorial side. You too can be a co-author if you just pony up, and if you're an editor, well, you can earn extra cash by slotting these papers into the journal. An especially good route to that has been the "Special Issue" racket, where a group of themed papers are rounded up by a guest editor'

https://www.science.org/content/blog-post/just-bribe-everyone-it-s-only-scientific-record