"There are more requirements everywhere but in the States"
No. That's simply not the case. One easy refutation of this is the general education requirements referenced above which are nearly universal in the US and Canada but which are not part of the college curricula in most other Western nations.
Beyond the undergraduate degree, a typical PhD in the natural sciences in the US is 5-6 years after the undergraduate degree. In the UK, it's about 3, with similar numbers in continental Europe. There are a number of reasons for this, particularly the structure of funding, but one of the realities is that graduate education within the US involves at least some graduate-level coursework, while that is very rare in the sciences in the British, German, or French systems. It's also the case that students who receive their doctorates in Europe are typically required to do longer postdoctoral work to be judged as equivalent to a student who did his/her doctorate within the US. Due in large part to the longer time frame of a US doctorate, most US-educated students will have more publications under their belt at the time they graduate than will be true in Europe, and thus be judged as being further along on the academic career track.
In the larger points in this discussion, I feel several people are talking at cross purposes because they're engaging in different debates. Distinctions need to be drawn between:
University education versus K-12 education. The US is clearly much stronger in the former than in the latter. There is a reason why our universities attract so many foreign students, particularly in the sciences and engineering, and why the graduate programs are an even greater international draw.
The average university versus the elite university. In part due to the sheer size of the US, we have many more universities than most western nations do. Even if the educational attainments of the median students were identical between, say, the US and the UK, you would expect a greater proportion of the top-notch universities to be US rather than UK ones. All three of the universities I've attended happen to be on that list of the top 200 universities, ranging from number 6 (Stanford) through number 101 (Southern California) to number 163 (Michigan State). I can tell you that the average abilities of the students at these institutions varies markedly, and these are still among the elites. 3rd and 4th tier universities in the US are clearly not the equal, on average, to the better schools around the world. At the same time, no country on Earth has an educational system where the average student within it is equal to the average student at Harvard or Berkeley (the most frequently cited top US universities in the private and public spheres, respectively).
(Imagine two bell shaped distributions with identical means. Make one of the distributions 5 times as tall as the other one. Draw a line representing the top 5% of all institutions. Note that many more of them will be from the taller distribution, even though the two have the same underlying pattern, because of sheer weight of numbers. Simultaneously, more of the bottom 5% will also be in the higher distribution. The underlying notion is that with a larger sample size you will have more values at the extremes of absolute values in the distributions, even with identical means and standard deviations.)
A caveat also needs to be attached to the surveys of what high school students do and do not know. International assessments are occasionally taken, and clearly identified as such. Students are well aware of the fact that the answers they provide on such assessments will not count toward their grades. As such, there is little motivation to perform at one's best, and a certain juvenile humor involved in giving adults a heart attack that one is incapable of finding one's own country or state on a map. With a US culture that purports to value independence and rebellion against authority, this is an entirely safe form of rebellion which can insulate a student's self-image without having true consequences on his/her life.
In regards to the original points:
- The amount of grading done on a curve varies tremendously both within and between universities. Introductory classes are typically curved, particularly in mathematics, chemistry, biology, physics, economics, and psychology. Upper division coursework rarely is, and is more often presented in seminars and discussions rather than in large lectures. Many courses in the social sciences and humanities are graded primarily on the basis of term papers, which are very rarely graded on a percentage system, and consequently rarely curved themselves.
- The idea of competing against each other is itself based on a curve. Without a curve, there is no competition from one student to another.
- The pass grade itself is highly variable from professor to professor and course to course. I know in my first semester of physics, the pass grade was somewhere around a 60. In my second semester, it must have been much lower as there were only 3 of us in a class of ~170 who were above a 40%.
- Undergraduate college degrees are indeed required for medical and law school. Most students planning to become physicians take an undergraduate degree in biology (as medical schools require 2 years of biology, 2 years of chemistry, a year of physics, and a year of mathematics anyway, a major in biology is not far beyond that). Many students planning law school study political science and/or economics.