I think the difference is that, better schools and private tutors, are at least in theory, teaching useful skills and ultimately creating a better person at the end. Being good at the SATs doesn't have the same excuse, so its much more obvious when you're basically just paying to get a better score.
Look, I don't disagree with you -- other than the score SAT prep is fantastically bad education investment. But I think this is a problem with the testing more than some larger class issue. We've rewarded learning a bunch of useless facts and test taking strategies. You could probably switch out the SAT for an entire test of movie trivia and you'd probably get the same distribution of performance since ACT/SAT just reward the people who study for it the most. You can't accidentally prepare for these tests by other schooling that's not geared for it.
