Yeah, I'm not sure if this is true, but I have the impression the error rates have increased in the last decades, despite spell-check becoming more effective at finding them at low cost.
I recently read all of Philip K Dick's novels. Spotted typos in every book. I log typos in my goodreads reviews
In the past it wasn't even the author's fault necessarily. The worst case of this was an anthology of Ursula Leguin, "Five Complete Novels" where I quit recording the typos as there would be multiple per page
If the typos are in a legitimate eBook copy, it's because sometimes the people who make the eBook don't have the source file(s), and instead have to OCR a printed book.
There are some publishers I won't even buy books from anymore, because I've paid too much money for books that are so rife with typos and nonsense that it was clear that it never even touched the inbox of an editor or a proofreader.
In the past it wasn't even the author's fault necessarily. The worst case of this was an anthology of Ursula Leguin, "Five Complete Novels" where I quit recording the typos as there would be multiple per page