If HBD is true, then all the existing correlational and longitudinal evidence immediately implies that group differences are the major reason why per capita income in the USA are 3-190x per capita income in Africa

Don't agree at all. Differences in political culture are probably much more important.

Once the Chinese stopped caring about whether the cat was communist or capitalist, and focused on whether it made money, their per capita income was off to the races.

Interesting graph of the divergence of their per capita GDP from India right around 1980. https://en.wikipedia.org/wiki/Historical_GDP_of_China