In the current issue of Texas Monthly Jack Herrera has a top notch story about illegal immigration in Texas. After a portrait of a Honduran migrant who's chased away from home by rising gang violence and is desperate to land a construction job in the US, he writes about the main reason for the recent spike in border crossings—one that I've also tried to highlight:
Arguably the most important factor—one too rarely considered—is the interplay of supply and demand. In 2021, as the pandemic began to ease, “We’re Hiring” signs started to appear in the windows of businesses across the U.S. Acute labor shortages hobbled entire industries, interrupting supply chains and fueling inflation. In response, a record number of workers crossed the southern border.

Hererra then focuses specifically on worker shortages in Texas's booming construction business:
The deficit in construction is historic, by some measures.... Texas building executives are speaking in apocalyptic terms about the labor shortage they’re still facing. Behind closed doors, they bluntly acknowledge that countless new projects won’t get off the ground unless they hire workers who are in the country illegally.
....The industry also faces a labor-force problem it cannot address quickly simply by raising pay. For two decades, the number of U.S.-born workers entering the construction trade has nosedived.... Cutting off the supply of undocumented workers, then, would be like cutting off the supply of concrete and lumber.

....Whenever Texas politicians threaten to pass laws that would make it harder for businesses to employ undocumented workers, phones in the Capitol start ringing. Stuck with the need to show their base that they’re cracking down on migrants, politicians, including [Governor Greg] Abbott, have instead found a middle ground: They keep up their bombast regarding the border, but they avoid stringing any razor wire between undocumented immigrants and jobs in the state’s interior.
Herrera's main takeaway is that Texas politicians deliberately do things that get public attention—Project Lone Star, high profile disputes with the feds, busing immigrants to New York—but that won't make a dent in the numbers. That's because the business owners who really control Texas politics won't abide anything that actually works. So the charade continues.
In 2017, after Donald Trump first moved into the White House, his acting ICE chief, Thomas Homan, declared that he intended to increase worksite enforcement by “four hundred percent.” He largely succeeded. By the end of 2018 ICE had quadrupled investigations of undocumented workers, and agents had arrested seven times as many immigrants in workforce raids compared with the year before.
But one metric stayed virtually static: the number of managers arrested for hiring undocumented immigrants. In 2019 the Associated Press reported that convictions of managers who hired workers without legal status had even declined.
Williams made an argument I heard from Marek and others: that the government doesn’t have an interest in shutting down construction projects, which is what would happen if it required contractors to hire only legal workers. Of all the immigration-related crimes to prosecute, why go after those building the houses the country so badly needs?
It's not just construction, of course. And there's an obvious solution: mandatory E-Verify and real penalties for employers who violate it. But precisely because it would work, Republican business donors oppose it and Republicans, therefore, aren't much interested in it.
The simple truth is that there aren't enough legal residents to fill all the jobs in the US. Everyone knows this. When Donald Trump thunders about deporting every illegal immigrant in the country, it's just empty talk, red meat for the rubes. In reality, our economy would collapse without immigrants, and no one wants to risk that. So we continue appealing to xenophobia with walls and agents and raids, but it's all theater. As Herrera notes, it's just enough to keep illegal immigrants scared and exploitable, but always stops carefully short of making any meaningful dent in their numbers. Quite the coincidence.