Ok, first off, it's a Visa, Luis.
Next, I think we are a country of immigrants, we are just slightly selective about which ones we'll let in. For instance, if you tried to get in, you probably would, you're educated, speak english, and have some idea of our history. Now the mexican that lives on the border town and steals to eat, speaks spanish only, but can't read or write, will probably not get in. Fair? Not quite, you have a chance to make a life for yourself there, while the other guy doesn't have much of chance where he is, but might if he moved to the US, even if he did pick vegetables for the first five years he was here.