I thinkt he U.S. education system is pretty decent and reflective of the society. How much you want is how much you put in. I think I read an U.S. news article a few years ago that said while the average aplitude are lower, the U.S. students actually do decent in high level math and science competitions. The difference is that with Honors and AP classes and the like, the students that want to get ahead will take the challenge while those that don't falls behind. Look at any of the course materials from a good competetive high school's AP and honors system, you can tell these going to be hard courses. Lastly, another thing I liked about U.S. style's of education, I was talking to this engineer that went to France to study abroad. His view was that the French students had much superior fundamentals that comes from a much more strict and stringent learning system. But when it comes to some thing that needs initiative and creativity like programming, they have a lot more trouble with it. Another example would be what my parents told me about a lot of students from top colleges in China. While they've memorized and enshrined a ton of knowledge in their brain, they don't know how to write a good thesis when the time comes. The top students are so used to being told what to do and learn their whole life that when they need to branch out and do something of their own, they have a ton of trouble.
Well a lot fo TA's need the money and being a TA is one of a few work study jobs. They can't really work anywhere else since they are foreign unlike most American kids and permanent citizens. Also when the time for internship in a lot of tech industries comes, not a lot of companies are willing to hire a foreign student unless it's some one really special. Not to mention the defense industry that hire citizens only. But yeah, calculus is definitely needed in engineering, financial (business models), bio medical and other professional jobs.
