I'm no fan of "big publishing," but they do a/b test learning objects... This is a labor intensive job. That is why a new textbook edition costs historically 1M to produce(200k for a re-release).
Or did you think everyone learns best the same way?
Wouldn't that make sense? I feel like bad textbooks have given the idea of text books a bad name. And I don't think this is a "no true Scotsman" fallacy. It's more an issue of mostly horrible Scotsman written to align with ridiculous state standards.