(I don't know exactly how books are published these days, but I assume that a computer is involved and that it should be a simple exercise for a competent proofreader to make corrections using some form of text editor prior to publication. Of course, it is entirely possible that these errors were present in previous editions, but there is no reason why they shouldn't be corrected.)
Yes, it should be a simple exercise but even major publishers rarely employ proofreaders any more. As Mud Puddle Books Inc. calls itself "a publisher and packager specializing in the bargain market" I think we can assume it too cuts costs where it can!
My own copy of the book is a 1963 paperback edition revised by the original author. I can't pretend to have read it from cover to cover but I've yet to come across any typos or the other errors mentioned.