I'm all for handwritten tests, but it's more complicated than that. If you're actually writing for 2hr+ and haven't studied appropriate technique or bought some sort of crutch like a pencil holder then the repetitive motion will absolutely cause cramps for a fraction of the class regardless of being 20ish and healthy, and they might not find that out until they're forced to write for 2hr. The muscles manipulating a pencil (with poor technique) are much smaller than those manipulating a post hole digger, so that comparison isn't fair.

What are you even talking about? It’s normal for young students to be using a pencil to write for multiple hours in a day in school.

With breaks, and it's also normal that in a class of ~30 you'll still find a couple students with cramps.

A good exam also has breaks between writing because you need them to think about what you are going to write. An exam that is just about writing down words as fast as you can is going to suck whether that's handwritten or with a keyboard.

Won’t someone think about the students who get cramps from typing on keyboards as well??

Not in my experience, nobody complained of that during my studies. 74 exams over 5 years ca. 2h long, also 2h long lectures, often without pause, back-to-back with another such lecture (but max 2 in a row)

Nothing to do with weight. It's a cramp in the muscles of the hand from holding the pen and making fine movements for hours. I'm guessing you are from a generation after keyboard use became common, so you haven't encountered it.

Right and wrong. I am of a generation before common keyboard usage. As far as writers cramp goes, we all got it from time to time. At worst it was a minor nuisance compared to the skinned knees, bruises, and occasional broken bone that we racked up recreationally.