American immigrants that arrive legally are treated quite well. The first year earning average is about $7500. (these are approximations) and the second year is $15,000 annually. Those are higher wages than most of the world.
Alternatively, illegal migrants subvert the wages of the existing legal workers by providing cheap under the table labor. Supply and demand applies to labor as well as production. There are numerous corporatist sycophants that will say that illegal labor supply has no effect on wages or the environment and are positive for Wall Street and the economy. Creative writing in economics is a useful tool for the powerful.
The left and Christians have provided a lot of support for illegal aliens in the U.S.A. In Oregon many communities have illegal alien service and support centers, and many cities have declared themselves illegal alien protection areas in a mild insurrection from support for Federal law.
The basic problem with illegal aliens is really demographics; there are tens of millions of them and they tend to be on a Trump trash-the-ecosphere- kind of job socialization. Being from poor countries usually they haven’t much concern about the environment. That culture will reinforce a generation or two ahead of workers and just consume and work without much concern for abstract ecospheric conservation or restoration goals and select other political concerns of the more prosperous. If the U.S.A. is already over-populated in relation to the ability of the ecosphere nationally to sustain the economy too far in to the future there should be a concern about limiting the opportunities for illegal and legal immigration until a global ecospheric restoration and ecological economic reform is created.