Coaching and tutoring has diminishing returns. Simply having done the practice test before the actual one would both significantly boost the score while reducing the anxiety. The tricks are not hard to learn, and practice tests are cheap to buy (or borrow from library). SAT is (was) probably the cheapest way to boost admission chance for a poor student compared to extracurricular, competitions, volunteering, etc. Those with money always have an advantage, but standardized test like SAT is probably the most egalitarian, as everyone has to take the tests by themselves in a controlled environment.