I dont know about any other country but its quite hard for an average mexican to come into the US legally, in order to get a passport you have to have $$$ in the bank and quite a bit of it and you have to have properties so you can prove your planning on coming back. And all these requirements are nearly imossible to an average mexican. I was once told by a friend who was here illegaly that if he had all these requirements that he had no need to come into this country to seek a better fortune if he already had properties and $$$ in the bank.