Some people claim that it's unfair to put the burden on employers not to employ illegal immigrants -- that if the job applicant claims to be a citizen, and waves what looks like a driver's license, he is reasonably believed and the employer shouldn't be penalized for not checking any further. Yet we demand a higher level of scrutiny for a woman who wants Medicaid coverage for her three year old's heart surgery, because we're worried about illegal immigrants' using the American social service system.
I can see how from a certain viewpoint, this seems reasonable. Sure, if the "illegals" are going to come anyway, might as well have them work for otherwise-below-market wages and keep prices low and jobs in the U.S. against the recessionary day when Americans are willing to work for those wages. But don't have them steal resources out of the society by taking their kids to the doctor. From a more long term perspective, however, what seems to attract the greatest number of immigrants, both legal and illegal, is the prospect of a job, not of social services. If I were going to move somewhere for the government health care and outcomes for poor people of color, I'd pick Cuba way over the U.S.
To be serious about curtailing the supply of undocumented workers, we need to reduce the demand for their services. The federal government seems unconcerned about the number of citizens who can't obtain health care promptly because they lack the proper paperwork, so why stress if citizens also are slowed in their pursuit of employment by a few days to check their claimed Social Security number against the federal database? I realize that any lag increases the transition costs of labor and may reduce our economy's flexibility (fired today, hired tomorrow!), but this only increases the incentive to develop faster methods of verifying work eligibility, as well as employers' incentives to offer sufficiently decent wages that those who can offer pre-approval from a prior employer will be interested in the job.