Well, there is some basic high value prep like test familiarization, determining guessing tactics, and the like that take little time and effort and do not require a test-prep course.
Of course, it is true that many of the parents and students here (not necessarily Asian ones) seem to have taken up the hypercompetitive tiger mentality, though perhaps not to the extreme of Amy Chua. E.g. common mantras around here are that one should take the AP course before taking the SAT subject test, or that not taking calculus in high school makes the student “behind”.