I am quite ignorant about how US high school system works and that's one anecdote I had heard, so I apologize about not being able to carry on a meaningful discussion on that topic, but that's just an example, and my core points stands regardless: there are huge differences between various fields that fall under STEM, and they should not be thought about as a single bucket. That's certainly true beyond high school as well.
That's quite true. With CS you can get hired right out of college but with other fields like bio and physics more schooling is required. I don't think a lot of students in the US want research positions (or qualify for them). So yes I believe that you're right it's an apples to oranges comparison.