The pricing framing in the article confuses cost-to-produce with willingness-to-pay. Two completely separate things. A book costs $4 to print and $25 at retail not because of margin gouging, but because the price reflects value-to-reader times conversion-elasticity, not the printing line item. Same thing happens in services. Agencies that cost-plus their pricing leave 30-50% on the table because they're solving for cost recovery instead of value transferred. The signal is always "what does this make possible for the buyer," never "what did this take us to make."
Using the cost to print instead of the full cost of production is very misleading. Someone needs to write, edit, typeset, market, etc. the books.
Most books don't sell a ton of copies, so there usually isn't a lot of profit left over after those costs.