I agree, I absolutely hate reading basically everything other than novels/non-fiction narratives in epub. All the work they did laying out the pages is just thrown away! Trying to read any sort of instructional book as an epub is straight up infuriating.

I work for a children's reading platform, and the book publishers universally send us PDFs of everything. We have a bespoke system to convert the PDFs into SVG for higher flexibility and added interactivity.

Literal Kids board books are getting a better treatment!