22B, there are plenty of applicants to elite schools with SAT scores of 2250+ or ACT scores of 34+. Once you get to scores like that, the difference between the great score and the perfect score is just a few questions (just a couple of silly mistakes). There really is nothing to choose between the great score kid and the perfect score kid (and you would see lots of kids with tons of 5s in AP exams in this group too).

The schools need some reason to choose one kid over another. Sometimes it may come to something really random, but there have been Ivy admissions folks that have stated that probably 75-80% of the kids are qualified applicants. That is why ECs come in to play.

I also get the impression that in other countries one attends a rather specialized university. My eldest is going to study abroad next semester, and she was choosing between a university that specializes in political science versus one that specializes in economics. Maybe this is wrong, but I have the impression that other countries don't have/don't value the LAC experience, and instead expect the kids to specialize at an early age. Those schools can have special admission exams. But if most kids go into US colleges undeclared, it isn't really useful to base admissions on some insane math test mentioned in previous posts...most kids will never do (or need to do) that kind of math.