With the possible exception of Bangladesh, the purpose of this exercise is to explode the common myth that these countries are poor because they are overcrowded and America, having plenty of room, should just let them all in.
Couple this with the fact that most of them will not head for the comparable population density areas noted but straight for our cities where they can live in their little Balkanized enclaves. Although, at least in the case of the Los Angeles area, it is a huge Balkanized enclave covering most of several counties.
Great points.