I think the implication is that fact checking an entire book is more effort. One would think errors in a book are evenly distributed without any reasons to beli

I think the implication is that fact checking an entire book is more effort. One would think errors in a book are evenly distributed without any reasons to believe otherwise. I'd be biased towards thinking the introductory chapter received more editorial attention than the rest of the book, so it is possible the rest of the book contains more errors per page.