If hiring illegals were NOT tax deductible, then the IRS, the most feared beauracy in all the land, would take care of this problem in nothing flat.
It would shrink the problem anyway. We’d still have to get rid of the ones who came here not to work but to steal and murder, but at least it would be more managable.
What happened to the wall we’re supposed to build? That would work for at least some of the bad guys.