It is meaningful

when the tests are given to very young kids and the uneducated adults. For young children, if she or he gets some kind of training, like counting, recognizing shaping, and some language skills, the test scores are likely not reflection of the real intelligence.

Another point to explain your observation is that the parents of the children you met have higher than average IQ so most likely their children do too. It is not always individually correct but it is statistically correct.