One of my teachers in high school used to routinely lose our homework assignments and exams on her desk. She was very forgetful...I don't 'get' people like that. Do they somehow think it's not disrespectful to students?
I had a colleague who had the habit of disappearing during the last week of classes- the rest of us got tasked with dealing with his students who were bringing in their papers. We would open his office, and place them on his desk. One semester, he gave about half a class horrible grades, because 'they didn't turn in the final project'. It was only after other faculty said, 'I personally put that paper on your desk!' that he muttered that he'd let the students re-submit their work.
Some time around spring break, he came into a faculty meeting, dying with laughter. HA HA HA! He'd just found the pile of papers , stuffed on his bookcase! HA HA HA! Why, he must have moved them over there and forgotten about them! (I'm using capitals to indicate the extreme loudness of his laughter, and because he literally did laugh like that, sort of barking HA's.) He didn't understand why the rest of us didn't find it hilarious.
She was one of my favorite teachers. She would generally either have us print her new copies (if it was a report she lost) or give us full credit (if it was a handwritten in-class assessment she lost). For the most part, we would have received pretty good scores on those assignments anyway - it was an honors class and we were all good students. I had her for four years - I was fairly accustomed to it by the end. Every once in awhile she'd find stuff from the last marking period and give it back to us
She also got better about it by the last year - I think she realized that some students were claiming that she'd lost work they never turned in at all.
That reminds me - my best friend at the time committed Student Darwinism in her class. He turned in a "research paper" that was almost entirely plagiarized from the internet. It was especially noticeable because he'd neglected to un-link the hyperlinks to other webpages, which printed out blue. He managed to get away with it by claiming that those were his sources (which we were also required to turn in) and he just happened to forget to turn in the report and format the first page of one of the sources so that it looked like the first page of his research paper
I wish she'd thrown the book at him that time - later when we were working on a partnered project he tried to throw me under the bus in a similar fashion.