Most books have trivial layout and typography - simple, successive paragraphs with a few very minor embellishments such as the occasional large header, page-breaks before chapters, and page numbers in the footer. Preventing widows and orphans is definitely not the norm - just browse your local library or bookshelf. I seriously doubt people worry much about rivers, too.
Books with diagrams and side-notes tend to have more complex layouts, sure - and that's most educational books. Maybe there these typography issues are given more attention, but it's pretty clear that the typical paperback has demonstrated they aren't that important to readers (which isn't a judgement, it's just the way it is), so I wouldn't be surprised if almost no books worry about these issues anymore, beyond perhaps using software which addresses them insofar as they can be automatically.
Books with diagrams and side-notes tend to have more complex layouts, sure - and that's most educational books. Maybe there these typography issues are given more attention, but it's pretty clear that the typical paperback has demonstrated they aren't that important to readers (which isn't a judgement, it's just the way it is), so I wouldn't be surprised if almost no books worry about these issues anymore, beyond perhaps using software which addresses them insofar as they can be automatically.