Earlier quoted context omitted.
You mentioned publishers leave you with 10% of the sales. I can't wrap my head around that, how is that possible and acceptable by authors?
It's worth noting that the 10% vs 80/95% figures are comparing different totals. For a traditional publisher, the 10% is against the price of the book (depending on the contract this might be against cover price or against the price the publisher actually receives from the wholesaler). It's not , like the self-publishing platforms, the percentage of net profit after costs like printing etc.
And once upon a time, buying, inking, moving pulp was not cheap.