Also, all the mexicans you see working on the roads? Those companies are not paying them under the table. They are working government contracts and file w-2/w-4 forms, 1096 - M and 1099 - M, however they are paying people.
As for picking cotton or lettuce, hey, it's there. The job is there. You don't have to be mexican to do it. You just have to be willing to work.