Textbook publishing has a complex product lifecycle driven by user feedback
Textbooks are a significant investment, especially for the large, foundational college courses with huge numbers of students per year. You're not just creating a static book. You're creating specialized art and illustrations, some number of print ancillaries (e.g., student study guides and instructor resources), and a growing array of complex digital products. A single introductory textbook package can carry an initial investment of several million dollars.
A textbook product team often has one editor who owns the whole product line—think of them like a product owner in a technology company. There are then other team members who own other pieces of the products: the detailed content development work; the art program; the physical production of the actual product; the marketing effort; the sales effort. Typically, there are also a number of outside vendors who must be managed. Rarely is there a luxury of focusing on just one product. Most of these publishing teams are juggling multiple complex product lines on competing timelines.
When an editor identifies a product opportunity, they must first sell the business case to their bosses. Then, potential authors are identified, often by sales representatives who have detailed knowledge of a particular market. After a selection and vetting process, an author or author team is finalized and set on the hard path of drafting the content.
Content and digital products are tested with users at every step of the product life cycle. Everything goes through many iterations before the product is published and shipped; revisions are based on user feedback.
If this is starting to sound like an Agile development environment, it does have distinct similarities. This is the way it was done in publishing even before Agile was really a thing.
Moreover, we were doing human-centered product design before it had really found its place in the mainstream.