American child-rearing and American education are more tolerant of failure. Top American students have learned how to lose gracefully as well as how to win gracefully. They have been taught that risk-taking is worthwhile.
If you look at the distribution of academic scores in American primary, secondary, and undergraduate education, you will find that the American education system has institutions that are consistently very poor, institutions that are consistently mediocre, and institutions that are consistently strong. Depending on their resources and priorities, Americans gravitate toward the institutions that seem to suit them.
A top secondary student who wishes to attend a premier undergraduate school needs to focus on certain things. In Asian countries, the student should cram to pass tests. In America, the student should split their effort into essay-writing, math, science, and athletics. Most premier American undergraduate schools can easily fill their student bodies with students who have high academic marks. Athletic striving helps distinguish applicants as being "well-rounded".
American secondary schools have well developed inter-scholastic leagues in many sports. In each contest between schools, one school wins, and one school loses. Occasional failure is expected; effort and improvement are demanded; coaching is provided; and success is honored. Success is simultaneously measured on a personal improvement level, in contests between individuals, and on a team level.
Courses like MIT's "2.70 contest" have been replicated at several top engineering schools around the world. Instructors of these courses have noted the wide variety of approaches and successfulness of MIT's students, as compared to other countries' students. At MIT, it is normal for one-third of the students' machines to fail to score any points. On the other hand, some MIT students' machines are wildly aggressive and/or wildly successful. In prestigious European and Japanese engineering schools, nearly all students' machines score some points -- in identical contests -- but few students take the unconventional approaches needed to be wildly successful.