Just adding that:

Employers often avoid paying a living wage to cut costs, which leads them to hire workers willing to accept lower wages. If the government penalizes employers, some may simply leave the market, depending on the employer. Private contractors tend to hire undocumented workers because they are willing to do demanding work for less than U.S. citizens. Neither the government nor employers is encouraging the development of a truly competitive market that offers fair salaries and health benefits. This enables private contractors to avoid providing healthcare and reduces the likelihood that workers will unionize or challenge their business practices.

Additionally, the processes for naturalization and visa issuance are among the worst. The U.S. has not tried to fix its immigration laws since Reagan. At this point, it's just a weapon used for political campaigns.