If I were to nitpick, I would say that they try to move to a idealised version of the US that never quite existed. This romanticised version has been pervasively depicted in mass consumption media for many decades.

More meaningful perhaps would be to count the immigrants from developed countries and immigrants that earn above the median in their respective countries and/or go to the US and earn above the American median.

There are a lot of desperate people in the world right now who’ll take extreme action to escape their immediate predicaments, such as risking a Mediterranean crossing from Northern Africa to Europe.