Actually, the problem isn't that the ruling elites don't get it. They do get it quite clearly: the problem is that ordinary Americans are the ones who don't get it.
Don't you guys think it's a little odd that after 12 years of Reagan Bush ( and now Bush again) that not one Republican administration has done much to crack down on illegal immigration?
The reason is fairly simple: Republicans like cheap labor and economic growth through population growth. So, in other words, they won't do anything about slowing or stopping immigration because it would hurt the US economically.
Or rather, it would hurt the US's elites economically. Whether immigration affects the little people doesn't really matter to them that much.
It's not that hard or costly to build such a system. What's hard is getting some of your fellow AMERICANS to go along with it.
In order for such a system to work, you'd have to actively discourage the hiring of nannies, agricultural workers, waitresses or people from any other job that involves paying people under the table.
A labor force made of illegal immigrants is something that is that many corporations actually desire. It's a workforce that can't go on strike without fear of deportation, and that happily accepts lower wages for the same reason.
I work at a large, well known American multinational based in the US. Of the 6 person technical team that I'm part of, only two are actually American citizens. The others are on visa, with the exception of one person who has a green card.
And guess what? I happen to be one of those guys working in the US under a visa. I long ago realised that the basis for visas in the US is only for the benefit of businesses. If the US really wanted to clean its visa system, it could.
That it won't is purely due to economic reasons, not political ones.