What skills do they have? Most have none. They end up in US agriculture doing jobs most Americans would refuse to do (especially for the pay offered). Meanwhile, they pay taxes (but cannot benefit from any benefits, as noted further up the thread). In reality, we're exploiting them. They aren't coming here taking away tech jobs, or office staff. They clean our hotel rooms and harvest our lettuce.

But all this could be solved if someone had the cojones to reform our policies so that we had migrant worker visas. Then we would know who is here, where they are, the work would get done, and they could avail themselves of police protection (right now they are afraid to call because they could be deported). But for reasons I still don't really understand, that's a political non-starter. So we throw money at fake solutions pretending that we're "fighting illegal immigration", and they keep coming across the border anyway.

Caveat: actually, most illegal immigrants are the result of overstaying legal visas. Not people hiking across the desert. The migrant worker visa would NOT solve that aspect of the problem.

This article is from 2019, but I suspect the situation remains the same.

theatlantic.com - Real immigration crisis people overstaying their visas

But in the past 10 years, visa overstays in the United States have outnumbered border crossings by a ratio of about 2 to 1, according to Robert Warren, who was for a decade the director of the statistics division at the agency that has since been renamed U.S. Citizenship and Immigration Services, and who is now a senior visiting fellow at the Center for Migration Studies, a New York'based organization.