In a lot of cases I think what happens is that an extended family pools their resources and sends their brightest young person to the US to get a start, then they start to come over and get set up in similar businesses with money from the first one who came.
I think you are right. I was just thinking of a Korean family who owned dollar stores and convenience stores in our town, they were opening up branches and bringing in family members to run them. Very entrepreneurial people.