Kids who aren't coached on the test strategy do worse. My high school did no SAT prep, and my parents weren't really aware of it. I was lucky in that I had an AP History teacher whose goal was for every kid to get a "5", that meant incorporating test strategy into the flow.

You needed to know stuff as the ante, but knowing the magic bullshit that would give you a good essay score was the key to get the top score. I increased my score ~120 points from taking the PSAT blind in 10th grade to the SAT because I understood at that point that strategy was key and found out about it.

All of this stuff is a red herring though. The nut of the controversy is that standardized tests correlate to IQ. IQ, rightly or wrongly, is perceived to be culturally biased.