Hmmm. I think you're overweighting IQ test results. It's not as though there is one single, gold-standard, test (or even type of test) for intelligence, and the tests that exist change over time. Like anything, they are also imperfect.
True, they are imperfect. I guess that my issue is that high IQ isn't considered necessary to be gifted and having a high IQ doesn't necessarily indicate that one is gifted in their estimation. Does that seem reasonable?
That and achievement
is considered necessary to be ided as gifted. No matter what other pieces the child has, if the achievement in the 95th percentile+ isn't there, the child cannot be ided as gifted. That seems to be a recipe for identifying high achieving kids as gifted and leaving out all of the underachieving and twice exceptional gifted kids.