Ill give credit where credits due. yes, its relatively relaxed and certainly in contrast to neighbors like Brazil.
I sort of had a problem at tigre recently. the border guy flipped through my passport slowly, looking at each page full of stamps, page after page, then he looked up and said, "are you living in argentina?" i explained that i spent part of each year here, ahem.
The usa is trying, hopefully, to get some control over the exploding immigrant population, so thats one of the reasons for these visas etc. We dont want the population of china, but the world keeps coming, burdening our entire society in many ways. we're proudly a nation made up of all nations. there just needs to be a little control now that the population is so large and breathing room is disappearing.
Just like what Banelco did overnight to ATM withdrawals, arg. could change its visa policy and completely change things.