Incentives:
DACA. DACA means the families are urging their children to go to El Norte unaccompanied and hope to find safe harbor. The progressives who laud DACA are also up in arms over human trafficking but somehow fail to see the connection between illegal immigration and human trafficking.
"Citizenship at birth" (14th Amendment) from having been born on American soil (current interpretation). Creation of anchor babies.
Companies that want cheap slave labor with no questions asked.
Punish employers who hire illegals. Track a gaggle of illegals on their way to work, find out who their employer is, refuse to do business with that employer. Hit them in the wallet. Deprive the fire of oxygen and it will be extinguished.
Think of Aesop's fable of the fox and the fleas.
The 14th amendment never gave illegals citizenship if born here. It was specifically worded so as not to do so. It doesn’t matter, the government just treats the Constitution as if it is whatever they want it to mean.