See but we know that things like nutrition, toxins like lead, education, wealth, family structure, infection rates, and other factors that also differ between nations affect intelligence. That's not even getting into Differential item function, the use of IRT vs fixed testing or other statistical and psychometric factors that may impact the measurements.
You can't just compare two samples without controlling for confounding differences.
Science can't even fully explain the Flynn effect, in which industrial nationals have had IQs going up 3 points per decade on average within the country, and people are trying to use IQ to talk about differences between sample populations.
You can always compare two samples without controlling for confounding differences. However, you need to controlling for confounding differences when you want to explain the differences. When we say there is a difference in IQ between two groups, we are not saying the difference is genetic. The raw difference in IQ does have a meaning by itself.
I do agree with you that there are questions regarding to measurement issues and confounding issues. But it is hard to believe all the group differences can be explained away by solving these issues.
You can't just compare two samples without controlling for confounding differences.
Science can't even fully explain the Flynn effect, in which industrial nationals have had IQs going up 3 points per decade on average within the country, and people are trying to use IQ to talk about differences between sample populations.