the type of personality who is drawn to be a professor of creative writing is rather different than that of one who becomes a professor of electrical engineering, and I suspect the first is far less inclined to fail or treat people harshly.

Now that is an interesting consideration. You could well be right in general. But my anticipation of personal experience is of getting treated more harshly from a professor of creative writing than of engineering. This is because I can far more easily elicit the desired behavior from the engineering professor. That is, the desired behavior of giving me top marks and interfering too much with my education. If all goes well I may even be able to avoid him learning my name.

With a professor in something less objective I expect harsh marking for not optimally conforming to the (possibly flawed) positions that I was supposed to have guessed in the assessments. I am also more at risk of harsh treatment for political reasons. Given that their way of thinking is less like mine I am less able to predict what sort of things will piss them off and so provoke grudges more easily. I may say something that seems obvious to me but incidentally undermines something they care about. Once that happens I am not all that talented at making bitchy people not be hostile. My instinct is to avoid situations where I am potentially vulnerable to capricious whims.

(Yes, my personal anticipation is different than that of most people!)