I've always thought that IQ-tests are biased towards education, too, and not just "raw intelligence". This seems to confirm it. The richer countries tend to have higher average IQ than the poorer ones.
(There's other wealth-related -- and, on a country-level, social-support-network related effects, too, as early childhood nutrition and other social-environment factors have an effect on IQ that, again, has been demonstrated on an individual level.)
The first sentence of the linked post, well before the actual maps, is "Please note: Quality of education greatly influences IQ scores, i.e. a lower average IQ is more indicative of lower access to wide-scale quality education rather than innate intelligence (as demonstrated, for example, here). Also, testing conditions influence results; wealthier countries are more likely to be able to afford better testing conditions for participants."
It's impossible to measure some pure form of "genetical intelligence". After all, this is the best strength of our species: we're born idiots, and we learn our way up. We adapt.