According to this article, the problem is oligopolistic markets: only 5 major book publishers exist, and they have no interest in competing.

The article also doesn't examine the consequences: are consumers getting as many books as they want? Is society better off with fewer books available? What about the effects on authors?

Oddly, neither phrase "copyright" or "intellectual property" appear in this article. That's the legal construct that underpins the oligopoly, though.

This article is pretty shallow. It barely scratches the surface of the issue(s).