They will typically have slightly different means (not far above the cutoff) and quite strongly different tails.
It's absolutely true that, if all you know about an individual is membership of one of these populations, then you know very little. Any new information about the actual person will quickly swamp this signal. If you've actually met A & B (or seen their work) then group membership is irrelevant. This is the situation in hiring people.
But it's also true that these distributions lead you to make predictions about the tails. While any one individual is vanishingly unlikely to win a Nobel prize, you can predict that (if they are fairly awarded) there should be a huge slant in how many go to each group. And I really mean huge, this ratio (if things are Gaussian, etc) grows exponentially in how far along the tail you go. Seeing such a skew is thus no evidence that hiring/prize-awarding is biased.
My point is really that individuals aren't defined by the distribution, just the number of individuals is defined by the distribution. But many people take these distributions personally.
"3.8 million students took the PSAT -- the practice version of the SATs ... 1.7 million students from the class of 2015 took the SAT"
Both side of the bell curve has poor definitions and IQ tests are far from perfect as it is said to optimize the accuracy between IQ 70 and 100. That said, we do see more men in practically every kind of type of data set for both side of the bell curve.
To cite a professor of both biology and neurology, no society on earth like to talk or even think about the mentally disabled. The "downsides" of greater variability is a group that most people treat as they don't exist, so I would not be surprised if many people really believed that the only explanation for a different top 1% is discrimination.
This is not a statement about the group average, but about the group variance. The SAT is not a good tool to use to assess group averages; I already mentioned this.
Yes, but the general concept is that the benefits and the downsides occur in different people. A single person doesn't illustrate "the benefits and the downsides" of greater variability any more than a single person can illustrate variability.
WRT issues of pure sample size, you can see one of the standard supports for GMVH in the SAT Total Group Report for 2018 here: https://reports.collegeboard.org/pdf/2018-total-group-sat-su...
Of the 2,135,788 students who took the SAT during high school, graduated (high school) in 2018, and had a gender, 1,117,329 were female and 1,018,459 were male. (751 had no gender.) 7% of the females, or ~78,000, scored 700 or above on the math section. 12% of the males, or ~120,000, did the same. So at the 91st percentile males are already outnumbering females by more than two to one after being pulled from similarly sized samples.
The greater-male-variability hypothesis says that males should equally outnumber females among low achievers. These tables don't support that -- 1% of females score below 300 in math, compared to 1% of males; 12% of females score below 400 compared to 11% of males.
The usual response to this is that we assume the SAT comprehensively samples high-ability students -- if you'll get a good score, you are strongly encouraged to take the test -- while mostly overlooking low-ability students, who may see no reason to bother.