Of course, no one is saying they are. But if immigration is unregulated, a sizable majority of them likely will be, because living conditions are vastly superior in the U.S. to most poor areas in South America. We already see this in illegal migrations. These aren't doctors and scientists, for the most part.
>or that immigrants measurably strain infrastructures (they don't) More vehicles don't increase wear on roads? More people don't increase demand for emergency services? Schools have unlimited capacity for children? How are you going to pay for all of this without at a minimum limiting the immigration rate? Our infrastructure is already crumbling. And we have enough impoverished citizens to put to work.
>The idea that immigration causes economic harm is contradicted by the tendency of business organizations and unions to favor it.
Well of course businesses favor cheap labor, and labor unions favor more bodies. What good is it for locals when businesses hire immigrants who are willing to work for free? Isn't it kind of a middle finger to people who built their lives here too, to force them to effectively lower their standard of living because a competitor is used to living on a dirt floor?
In spite of benefits, unchecked immigration does not come without cost. Regulations are absolutely necessary for preserving the standards of living of the state. None of this is xenophobia.