Anyone who is not here legally should not be allowed to work here. They must have a working visa, school visa or be an American citizen.
Those who hire illegal immigrants do so for cheap labor and pay them under the table.
If you cant pay wages, do the work yourself ( house keeping, lawn care childcare etc) or dont have a business.
Paying illegal immigrants only makes it desirable for more illegal people to come here.
Also, by not paying people who are legal citizens takes away from taxes used for schools and infrastructure.
People who hire illegal immigrants should be fined. If they are caught doing it again the fine should be larger than the first time. The third time they are caught, they should either be jailed or have their business license taken.