A writer, we assume, does his best to eliminate these pesky pests with multiple readings of his own, and readings from others upon who's eagle eye the author counts, unless, of course, said eagle eyes are pickled from too much gin and bitters.
But, alas, you can never get them all, apparently, even with three sets of "eagle eyes" doing the work, and then you put the damn thing up on Kindle, and somebody, perhaps the actor turning your opus into an audio book, after reviewing the script, says, "Hey, Snookums, you done got some errors in this here thang," and you scream, "Oh, fiddle faddle and farpleknocker," and suddenly realize why, perhaps, the release and reaction to the ebook in question has been like urinating into the ocean in an attempt to raise the sea level. Folks are downloading the sample, spotting errors, and saying, "Oh, heck no," before going back to the tee vee.
Well, it's a theory. Queries to the sets of eagle eyes resulted in a chorus of "I didn't see anythings", though one did admit, "I am the world's worst proof-reader." Gee, I wish she would effing have told me that before I paid her with a case of beer. Typical.
Anyway, said author is now going to review his manuscript again in an attempt to get the ones that got away. This is exactly how he wanted to spend his Fourth of July weekend.
Back in high school, I worked for a publishing company that not only did books but a monthly magazine as well, and part of my job was to catch typos in the magazine's articles. I was the fourth set of eyes, I think, and I always caught a few things, and when I asked my editor why I was still catching problems after three other people had looked, he told me that something always gets through, and often they don't find the last little errors until the magazine is published. I guess that's just the way of the world, but I don't have to like it.