If I were to get a H1B visa, I might want to do the work you currently do for a much lower wage than yours (since I come from an allegedly poor country or something like that). So, is getting a PHP newbie developer who was born in the USA and charges US$100K a year, or getting a good, talented programmer who will do the same work for US$60K a year... Is on the same level only because they will fill the same job position?
(I live in Mexico, and am *not* interested in living in the USA. I have a ~US$25K yearly salary, and live quite well off it. But many colleagues have migrated to the USA, just because of that salary difference)