I wonder if "preschoolers" in the first example refers to preschool aged children enrolled in a preschool. It would imply that the gifted are underrepresented massively in schools if that's the case, with most HG+ preschoolers in a home setting. That's one explanation that might reconcile the discrepancy, however unlikely.

Though, I think your interpretation of innumeracy is the more likely explanation for the baffling numbers!

What is to give light must endure burning.