Business owns politicians of all stripes. And as long as business wants to hire immigrants for cheap labor, I’m guessing they’re going to get to do so.
“The economy in the American Southwest was demanding half a million to a million workers… Setting a cap of 30,000 for Mexico encouraged more illegal immigration.” Source
One wonders why the border fence was left uncompleted in AZ. Is it because CA and TX have too many voters for that to ever work? At any rate, American businesses have been known to advertise south of the border for labor. We can’t be having good enforcement when that’s not what business really wants.
This is a site that purports to list the companies that employ illegals. I haven’t really looked too deeply into who’s running it, so it might be right-wing propaganda, but it may help you decide what companies to avoid if you want to indirectly affect how many people come over the border.