As an European, I did never have any IQ test, nor I know anybody who (to my knowledge) was ever administered an IQ test. I looked at some fac-simile IQ tests on the internet, expecially Raven's matrices.
When I began to read online blogs from the United States, I started to see references to the concept of IQ. I am very confused by the fact that the IQ score seems to be treated as a stable, intrinsic charachteristic of an individual (like the height or the visual acuity).
When you costantly practice some task, you usually become better at that task. I imagine that there exists a finite number of ideas required to solve Raven matrices: even when someone invents new Raven matrices for making new IQ tests, he will do so by remixing the ideas used for previous Raven matrices, because -as Cardano said- "there is practically no new idea which one may bring forward".
The IQ score is the result of an exam, much like school grades. But it is generally understood that school grades are influenced by how much effort you put in the preparation for the exam, by how much your family cares for your grades, and so on. I expect school grades to be fairly correlated to income, or to other mesures of "success".
In a hypothetical society in which all children had to learn chess, and being bad at chess was regarded as a shame, I guess that the ELO chess ratings of 17 year olds would be highly correlated with later achievements. Are IQ tests the only exception to the rule that your grade in an exam is influenced by how much you prepare for that exam? Is there a sense in which IQ is a more "intrinsic" quantity than, for example, the AP exam score, or the ELO chess rating?
Not at all. Knowing that doing X causes Y only informs that if you want result Y, the way to achieve that is by doing X. It doesn't tell you whether Y is desirable or not.
Hence, if a society wants maximum productive efficiency, and allocating more resources to their most intelligent members is the most effective way to achieve that, then yes, allocating more resources for them, and less for less gifted individuals, is the way to go. On the flip side, if a society wants, let's say, to maximize equality of outcomes among its members, then they'll completely ignore that means, and look for the method that will provide that outcome.
The decision about the "ought", then, is what truly determines which "is" will be chosen, not the other way around.