Why wouldn't royalities be based in "net sales"? I didn't finish reading the linked article to the end, because it is so long without much substance. Does it ac

Why wouldn't royalities be based in "net sales"? I didn't finish reading the linked article to the end, because it is so long without much substance. Does it actually describe any of the alleged manipulation of the "net sales" numbers? In the first half or so, all they mention is that "returned" or "exchanged" books don't count, which seems reasonable.