Interesting. This is what I've been thinking, especially after meeting with the principal regarding ds. She started off saying they have large gifted population (public school- and everyone wants their kid in gt program). Yet, when we showed her ds Wisc scores; she kept saying, "wow. These are very high scores." Dh and I found this funny since tester told us score was brought down by 2e issues and would be higher if retested later. Also, if the gifted population at school is so high, ds scores wouldn't be so shocking.
We had the same experience with our dd14 when we brought her WISC-IV & WJ scores to the school when she was seven. The district GT coordinator told me to homeschool her b/c they wouldn't be able to meet her needs and one of the school admin people we met with looked at the report and said something like, "wow, this really
is a gifted child!" It left me totally confused for the same reason as you: dd's scores were all over the place from low average on sections she refused to complete to 99.9th+ and the composite of all of that was not a DYS level score for instance, although still reasonably evidently HG. I didn't expect that to be a "wow" thing - it was just gifted and in line with where I expected all kids who were considered gifted to be at that time. Over time, I've come to realize that a lot of what they are seeing in their gifted programming are kids who have composite scores in the 70s or 80s (percentiles) on group tests with just one area in the 95th and certainly not composite scores in the top 1 or 2 percent, although achievement may be there. They also don't see a lot of 99.9th scores apparently.