That is enraging. I've seen similar things happen too and it blows my mind how ridiculous some of these teachers can be. I don't know if it's dehumanization of their students in their minds or an utter unwillingness to devote 30 seconds of directed attention to understanding the situation and making a reasonable judgment, but whatever the cause it is prolific. The only thing worse is when one of them will add something like, "life isn't fair, get over it" when it's fully in their power to make a reasonable determination.
It's a general problem with large bureaucracies. If you're a cog in the machine, the safest way is to always stick to the rules, and avoid any situation where one has to exercise discretion, since any personal judgment comes with potential personal responsibility down the line.
Aggression, Social Stress, and the Immune System – Takahashi, Flanigan, McEwen & Russo, 2018
https://www.frontiersin.org/journals/behavioral-neuroscience...
“Aggression has an adaptive significance for most animal species and is critical for acquiring and protecting territory, food, reproductive mates, and offspring. In animals with hierarchical societies, aggressive behavior is thought to help individuals gain and maintain higher social status (Box 2). It has been shown that aggressive behavior, especially the experience of winning, has rewarding properties in animals and repeated aggressive experience may lead to compulsive, pathological aggression that is highly reinforcing (Fish et al., 2002; Falkner et al., 2016; Golden et al., 2016, 2017).”
The flip side of this is from the professor's perspective: some undergrad in every class will lie their ass off about why their assignment was delayed.
Unfortunately, this reality produces no good options if you think someone is telling the truth: (1) make an exception, and be unfair to the rest of the class or (2) don't make an exception, and perpetuate unfairness for the impacted student.