Originally part of the pitch for cable television was that it was ad free. The networks discovered they could make more money by adding the ads back in. Peopl

Originally part of the pitch for cable television was that it was ad free. The networks discovered they could make more money by adding the ads back in. People were already paying for cable so they continued. There's no way to add ads to a book you physically have; you can't compare physical products to electronic products. If you make money selling a product there is a price point where you will make more by adding ads. It really is just a matter of finding the pricing.