I agree that these things should be taught in high school but they aren’t really one-and-done lessons - they are honed skills that take need to be practiced and refined. Gen ed courses really help with that more than stem, because as you said, stem classes require precise technical skills and profs likely aren’t going to spend precious teaching time in critical thinking, reading comprehension, or communication skills if they need to teach you Newtonian physics or biochemistry or something.
I went to a college with a strong engineering program. Presumably students would have to have done well in high school and on SATs to get in. Engineers treated college as a job prep program and were pretty blatantly put off by doing any gen ed coursework. So many companies and firms complained to the college about the graduates’ poor writing and communication skills that they had to institute a writing exit exam to graduate with a bachelors. All you had to do was write a 4/5 paragraph essay to some generic prompt - the exact sort of thing you do for SAT or AP exams. The pass rate was ~25% for graduating engineers! This was a few decades ago now, I imagine as ai gets more commonly used for writing assignments this issue will worsen… Or fundamentally change how critical thinking works in a way that I can’t foresee.