Actually, people who illegally cross the borders are criminals.
People who hire them with a nod and a wink are criminals, too.
It is a minor point, but they are not ipso facto criminals. To be a criminal you have to violate the criminal code -i.e. rape, murder, armed robbery, that sort of thing. You are not a criminal if you get a speeding ticket, or, if you build a fence to close to the property line and without a city permit - no matter how unlawful these things otherwise are.