I think you're being overly obtuse, and I'd request you try to work in good faith. If you doubt what I claimed, you can quickly verify on the wiki page[0].
In essence you aren't wrong, but that's not what we'd typically do in a zero (or few) shot setting. We'd be focusing on things that are more similar. If you want to understand this a bit better in what we might do in a ML context I wrote more here[1].
And I like Nico's comment about how different professors test. Because it makes you think about what is actually being tested. Are you being tested on memorization or generalization? You can argue both these kinds of tests are testing "if you learned the material" but we'd understand that these two types of tests are fundamentally different and let's be real, are not reasonably fair to compare scores to. I'm sure many of us have experienced this where someone that gets a C in professor A's class likely learned more than than someone who got an A in professor B's class. The thing is that the nuance is incredibly important here to really understand. And you can trivialize anything, but be careful when doing so, you may overlook the most important things ;)
Now... you could make this argument about geometry -> calculus if we're not talking about the typical geometry (single) class most people will have taken in either middle school or high school. Because yes, at the end of the day there is a geometric interpretation and we have the Riemann sum. But we'd need to ensure those kids have the understanding of infinities (which aren't numbers btw). We'd have to be pretty careful about formulating this kind of test if we're going to take away any useful information from it. Though the naive version might give us clues about information leakage (in our case with children this might be "child who has a parent that's a mathematician" or something along those lines). It really all depends on what the question behind the test is. Scores only mean things when we have nuanced clear understandings of what we're measuring (so again, tread carefully because "here be dragons" and you're likely to get burned before, or even without, knowing it)
And truth be told, we actually do this a bit. There's a reason you take geometry before calculus. Because the skills build up. But you're right that they don't generalize.
[0] https://en.wikipedia.org/wiki/Zero-shot_learning
[1] https://news.ycombinator.com/item?id=40313501