This implies that poverty is largely a product of being on the wrong end of the intelligence scale, which ignores the substantial impact that social and economic structures play in determining one's economic success. When looking at factors that perpetuate poverty, IQ isn't even on the map.
If you wanted to make it more meritocratic the populations with lowest IQ would actually be worse off, unless you also increase the minimal living standards.
I agree with this. I'm not sure that making economies more "meritocratic" is necessarily the only solution we have when confronting larger structures that perpetuate inequality. Even if it were, It'd be important to know who or what quantifies "merit." If it is impersonal market forces, the same unjust social systems will still eventually develop as certain families, classes, and countries entrench their economic development to solidify and secure an advantage down the line.
If you're talking about people who have some kind of mental handicap, then this is accurate, but I'm skeptical it will be meaningfully different for people with close to average intelligence or higher, because the effect of IQ will be dwarfed by other differences like how hard they work or how much they delay gratification and save.