There are lots of shades of gray that raise their head when it comes to typos. Some are a result of shoddy conversion; most, I think, are a result of lack of editing. I particularly find this to be true in self-published ebooks and in ebooks from very small publishers. Some examples of what I have seen in ebooks I have bought are found in
On Words & eBooks: Give Me a Brake! The problem is likely to increase as anyone with a computer, a word processing program, and a yen to write publishes their work through outfits like Smashwords and Manybooks. I suspect that this is the curse of the Internet Age and a symptom of the decline in education standards, along with publishers OCRing but not proofreading.