I just sent off my final changes to the copy-edited manuscript of The Scholar's Survival Guide. I had gone through it many times, others have gone through it, but in the end problems remained.
For compound words or terms, I used hyphens when I did not need them, and did not when I did need them. I got the number (singular or plural) wrong in more complex sentences. Commas at the end of lists did not belong. Commas setting off phrases did not belong. It goes on and on.
I notice such problems when I am reading other people's work, or my own work after a while. I try to make my students aware that such problems are likely to get in their way. But as an author, I am subject to errancy, as I guess all of us are.
Copy editors, and I am grateful for all of them, for almost all my books and some of my articles, made me a better more deliberate writer. Once in a while, they get it wrong, or we disagree. But, almost always, they are right.
Nowadays there is a tendency to have the author produce printer-ready pages, in effect doing the work that copyeditors and typographers do. This is especially the case in the LaTex world. But what is lost along the way is the keen eye of the ideal reader who saves you from your own idiocies. We confuse printing with publishing. Publishers do so much more, and I am not thinking of their business functions. They make sure that the printed work under their imprint is actually OK, to whatever standards they uphold. It's wonderful that amazon.com and others allow for the distribution of books by authors, but that is not publishing.