Agreed people have bad days. I would think it should be a policy that if that's the case, no glasses/contacts today? No work today so go home with a write up or go get your glasses/contacts. With potentially hundreds of thousands/millions of dollars passing through their hands per shift, there should be no exceptions. I was under the impression that at least at one point, it took 3 graders to assign a book a given grade. I'm guessing that must have changed down the line somewhere because that book is just crazy for the grade assigned.
Yes anyone can have a bad day but this looks like more than that. It's speculation but this looks like a labeling error and definitely a QC error. Something like this should never have left their facility.