you are right, its not random - but the USA has a lot to gain from someone like gamavor ( ). Here you have a highly qualified person, whose education was paid by another country, comes in, learns the language, starts paying taxes, spends hs earnings locally thereby creating even more jobs and hence more taxpayers - I know its a simplistic way of putting it, but people to country are like a resource, not unlike oil and gas etc. The more, the better, and the more educated even more better, escpessially if you dont have to pay for their education.