@Post no. 1: You are absolutely right. I believe that these day laborers (who are often Latinos/Mexicans) lower the living standards of working class Americans by competing against them in an illegal way (as in, these people agree to work for less than the minimum wage). Imagine if these people did not exist. Employers would then be forced to pay a decent wage in order to attract people to do these menial or dangerous or back-breaking jobs. The presence of the shadow workforce therefore drives down wages. They also prevent fair wages from being realized.
In my opinion, we should have even stiffer laws and penalties against unscrupulous employers who hire these shadow workforce people. I say that if a business is caught doing this, all of its assets, properties, goods, merchandise, everything, should be seized by the local government. The business will now be run by appointed/elected officials, it will actually be owned by the government to serve the greater good. I think this should be able to deter businesses from hiring these illegal aliens. If you do it, your business will be forcibly taken from you (and you will have deserved it, too).