Originally Posted by raac
Obviously they shouldn't be. If you're seeing unacceptable numbers of errors not present in the paper editions then contact your distributor and return the book. Additionally, write to the publisher and say why you did so. You didn't get what you paid for so don't wait around hoping they will fix it. They're under no obligation to do so. The :community should send a message that ebooks riddled with errors aren't acceptable.
You're right. Problem is most publishers don't listen. The epub i recently bought of Seth Lerer's Inventing English was missing all scans of historical documents and entire portions of text (which what remained kept referencing to the missing material). The publisher didn't even bother responding to me when i attempted to contact them.