Activists portray illegal immigration solely as a human story of the desperately poor from south of the border fleeing misery to start new, productive lives in the U.S. — despite exploitation and America’s nativist immigration laws.

But the truth is always more complex — and can reveal self-interested as well as idealistic parties.

Employers have long sought to undercut the wages of the American underclass by preference for cheaper imported labor. The upper-middle classes have developed aristocratic ideas of hiring inexpensive “help” to relieve them of domestic chores.

The Mexican government keeps taxes low on its elite in part by exporting, rather than helping, its own poor. It causes little worry that some $25 billion in remittances sent from Mexican citizens working in America puts hardship on those expatriates, who are often subsidized by generous U.S. social services.

Mexico City rarely welcomes a heartfelt discussion about why its citizens flee Mexican exploitation and apparently have no wish to return home. Nor does Mexico City publicize its own stern approaches to immigration enforcement along its southern border — or its ethnocentric approach to all immigration (not wanting to impair “the equilibrium of national demographics”) that is institutionalized in Mexico’s constitution.

The Democratic party is also invested in illegal immigration, worried that its current agendas cannot win in the Electoral College without new constituents who appreciate liberal support for open borders and generous social services.

In contrast, classically liberal, meritocratic, and ethnically diverse immigration might result in a disparate, politically unpredictable set of immigrants.

La Raza groups take it for granted that influxes of undocumented immigrants fuel the numbers of unassimilated supporters. Measured and lawful immigration, along with rapid assimilation, melt away ethnic-based constituencies.

Immigration activists often fault the U.S. as historically racist and colonialist while insisting that millions of foreigners have an innate right to enter illegally and reside in such a supposedly dreadful place.

Undocumented immigrants themselves are not unaware that their own illegal entry, in self-interested fashion, crowds out legal immigrants who often wait years to enter the U.S.

Increased demands on social services often affect Mexican-American communities the most grievously — a fact that explains why sizable numbers of Latinos support border enforcement.

What does all this complexity mean for the Trump administration’s plans to return to the enforcement of existing immigration statutes?

There is one red line to Trump immigration policies that otherwise are widely supported.

Most Americans want the border enforced. And, depending on how the question is worded, most voters likewise favor the completion of a wall on the southern border and an end to all illegal immigration.

There is little public support for sanctuary cities. They are seen as a form of neo-Confederate nullification — insurrectionary and unsustainable in a republic of laws.

Where controversy arises is over the more difficult question of the fate of at least 11 million foreign nationals currently residing illegally in the U.S.

Most Americans agree that if such immigrants are able-bodied but have no work history and are on public support, have just arrived hoping for amnesty, or have committed crimes in the U.S., they should be deported to their countries of origin. Nearly 1 million such people were already facing pre-Trump government removal orders.

Yet for those undocumented immigrants who are working, crime-free, and have established residence, the Trump administration will learn that the public supports some sort of accommodation that might lead to a fine, followed by the opportunity to apply for a green card.

Given those realities, the next immigration fault line will hinge on the definition of a “crime.”

For most Americans, identity theft, falsification of government affidavits, or trafficking in fraudulent Social Security numbers are the sort of violations that would end their own careers and unwind the very cohesiveness of government.

Rural or inner-city poor American citizens would go to jail for identity theft or lying on state and federal documents. Yet immigration activists sometimes seek to downplay these sorts of crimes as simply inherent in the desperate plight of the immigrant.

In sum, after the border is closed, and as long as the Trump administration does not summarily deport employed, crime-free, undocumented immigrants who have lived here for years, its reform agenda will quickly win the debate and at last return immigration to a legal enterprise.

In turn, Trump opponents will discover that while a small percentage of the undocumented have committed violent crimes, a far larger percentage than is commonly reported may have committed identity theft or falsified government documents.

Arguing to Americans that these are neither real crimes nor deportable offenses will prove no more a winning message for Trump’s critics than would deporting productive and law-abiding residents who entered the U.S. illegally win support for Trump himself.

— Victor Davis Hanson is a classicist and historian at the Hoover Institution, Stanford University, and the author, most recently, of The Savior Generals. You can reach him by e-mailing author@victorhanson.com.