Do employers take advantage of undocumented migrants?

In my experience, yes. While it is certainly not ethnical, I have seen employers hire undocumented migrants because they can pay them less, and many undocumented migrants are willing to do jobs that nobody else wants to do. Undocument migrants will, because of the fear of being reported or deported, complete work for below minimum wage, without complaint. This is attractive to employers as they do not need to pay as much to have unattractive jobs completed. Unethical employers, or employers who are struggling with money, often hire undocumented migrants to keep costs low. Many employers may also use the threat of reporting these migrants to refuse raises, fair pay, or fair job duties. This essentially silences undocumented migrants and forces them to accept unfair treatment and pay.