I'm not assuming anything. That was the evidence provided by OP's sources. The other examples in the article were posed as questions, not data. Otherwise my comment is largely anti-CFA and foreign controlled currencies.
Still the 'poverty leads to migration' theory is not quite true (in fact arguably the reverse in these particular circumstances), and therefore the fact some CFA countries have less emigration than some ex-CFA countries does not show that they are less poor or that the CFA is beneficial compared to non-CFA case.
I agree with your premise and I think there are two main reasons for this behavior.
Firstly even to migrate you have to have access to information and brain cycles to process it. Real poor are too busy to have that kind of time at hand.
Secondly even illegal immigration requires spending some money upfront and of course poor don't have it.
If you in the middle income range, it does make sense to move up the ladder by immigrating to a better place. If you are super rich, you can just buy citizenship.
