I mean, it's not so much the fear of deportation so much as the fact that lower wages go farther in Mexico. Most Mexicans who illegally immigrate do so simply because it makes economic sense. If the wages were so low that it didn't make economic sense to them, then they would simply return to Mexico voluntarily.

work for a fraction of minimum wage paid under the table.

The real irony here is that a lot of immigrant workers were here on legitimate visas, in fact a huge portion of the "illegal" immigrants who the Trump administration has deported were here on legit visas that he wantonly revoked, and were therefore paying taxes on the shite wages they were being paid. Taxes that the U.S. is now no longer collecting. Anyone wanna take bets on the deficit increase under Trump?