This prescient article from 2006, published in City Journal, explains in more depth:
Advocates of open immigration argue that welcoming the Librado Velasquezes of the world is essential for our American economy: our businesses need workers like him, because we have a shortage of people willing to do low-wage work. Moreover, the free movement of labor in a global economy pays off for the United States, because immigrants bring skills and capital that expand our economy and offset immigration’s costs. Like tax cuts, supporters argue, immigration pays for itself.
But the tale of Librado Velasquez helps show why supporters are wrong about today’s immigration, as many Americans sense and so much research has demonstrated. America does not have a vast labor shortage that requires waves of low-wage immigrants to alleviate; in fact, unemployment among unskilled workers is high—about 30 percent. Moreover, many of the unskilled, uneducated workers now journeying here labor, like Velasquez, in shrinking industries, where they force out native workers, and many others work in industries where the availability of cheap workers has led businesses to suspend investment in new technologies that would make them less labor-intensive.
Yet while these workers add little to our economy, they come at great cost, because they are not economic abstractions but human beings, with their own culture and ideas—often at odds with our own. Increasing numbers of them arrive with little education and none of the skills necessary to succeed in a modern economy. Many may wind up stuck on our lowest economic rungs, where they will rely on something that immigrants of other generations didn’t have: a vast U.S. welfare and social-services apparatus that has enormously amplified the cost of immigration. Just as welfare reform and other policies are helping to shrink America’s underclass by weaning people off such social programs, we are importing a new, foreign-born underclass. As famed free-market economist Milton Friedman puts it: “It’s just obvious that you can’t have free immigration and a welfare state.”
Immigration can only pay off again for America if we reshape our policy, organizing it around what’s good for the economy by welcoming workers we truly need and excluding those who, because they have so little to offer, are likely to cost us more than they contribute, and who will struggle for years to find their place here.(Of course, it isn't just the low-skilled jobs that are being undermined--Obama is working with high-tech industries to replace middle-class STEM jobs that pay decent wages with foreign STEM workers that are paid a pittance).
The expectations of these illegal immigrants is different as well. Michael Goodman writes at The New York Post:
The short bios in The Post and other places featuring immigrants who are in the United State illegally were fascinating. I was struck by their courage to leave their homelands, their pluck at navigating a new culture and their patience in waiting for America’s official welcome mat.
Something else struck me, too. Not a single one expressed remorse for jumping the fence or overstaying visas. The law was simply a nuisance, an unfair barrier to their right to live in America, and they felt no qualms about violating it.
Some of these immigrants, including one woman who sneaked in from Mexico 18 years ago, even complained that presidential amnesty doesn’t include free health care.
“It isn’t fair,” Graciela Flores whined.
What luck — she and the other 5 million who benefit have found their soul mate in Barack Obama. He’s not into obeying laws, either. And he is endlessly entitled to whatever he wants, whenever he wants it.
Oh, sure, he has twice taken an oath to “faithfully execute” the nation’s laws, and to “preserve, protect and defend the Constitution of the United States.”
But he’s not serious about oaths, either. As America has learned, his word is not his bond.
A president who cannot speak honestly and who finds the Constitution’s separation of powers an option he can ignore is the very definition of lawless.
“It’s fair to say we’ve never seen anything quite like this before,” a Temple University professor told a reporter. He meant the sweeping amnesty decree, but his comment also summarizes the entire Obama presidency.
There’s never been anything like it, thank God.But there have been other instances of this; in Germany, for one thing.