Nathan Newman makes a good point here:
Here's the core reason why I think most (not all, but most) of those saying they oppose immigration because of its effects of lower-income native workers are not really serious or, worse, just covering straight-up nativism with a faux charitable concern.
In the Bush 2007 budget, a grand total of $177 million was appropriated to enforce our wage and hour laws. Compare that to the $13 billion in the 2008 Bush budget for border enforcement -- nearly ONE HUNDRED TIME AS MUCH spent for border enforcement as for wage enforcement.
It's become something of a cliché to point out that hands-down the most effective way to stem illegal immigration is simply to slap meaningful sanctions on businesses that hire undocumented workers. (That, combined with increasing the channels for legal immigration, it seems, would do far more to regularize the flow of immigrants than building more billion-dollar fences and hiring more guards, which seems to accomplish little save for preventing undocumented workers who are already in the United States from returning back home.)
Now, there are creative ways to deter businesses--say, offering amnesty and cash prizes to undocumented workers who tattle on their bosses--and straightforward ways. But it goes without saying that any administration that's cavalier about enforcing wage and hour laws and willing to neuter agencies like OSHA won't take this approach seriously. Note, for instance, that 54 percent of contractors in the L.A. garment industry regularly violate minimum wage laws. The same goes for nursing homes and restaurants. Presumably those businesses aren't exactly deterred from hiring undocumented immigrants, either.