There’s a range you can improve on. If you are an idiot you don’t have a chance of improving that much, but mommy and daddy can buy you a 4.0 at a private school. Can’t bribe your way to a 1600 SAT anywhere near as easily as the private school game can be played. And this is another reason why I like SATs over grades - the poor can get a leg up over the rich.
I'll take a standardized test over arbitrary grades any day. Grades are far, far easier to game in so many ways (switch to an easier major!) than the SAT. Just ask anyone gunning for med school or law school - they will opt for the easier class over the harder one if it means their GPA has less risk of dropping.
