I have to agree, I know many homeowners who take advantage of cheap labor and hire cleaners, cooks, nannys, and housekeepers who have difficulty speaking english and are afraid to call the authorities when there is trouble. These are signs of undocumented workers. People who hire these people are not thinking of the law or their future electability or appointability, but they should.
When the task is contracted by the job, the homeowner has no liability to look for immigration status, but when the job is contracted by the hour and the employment runs for more than half a year, I believe the employer needs to consider the payroll tax and income tax situation. There are probably insurance considerations as well. If someone is employed full time (40 or more hours per week), it is even more obvious that one person is the employer and the other is an employee. (Not an independent contractor). I suppose if one wanted to verify an independent contractor situation one would look for a license and or a posted bond. And perhaps verify that the person has workers insurance in force while working on your property.
Illegal immigration is a serious problem that will become more important after another terrorist attack. Politicians need to be more concerned and not appointing someone who has contributed to the problem is a good start.