Why whenever there is a raid on illegals working somewhere you have Americans lining up to do those same jobs?

I am a retired Police Officer on the Ca. Az. Mexico border. I am so tired of people thinking that all illegals from Mexico are farm workers and are picking fruit. Cesar Chavez's Farm Workers Union have not let illegals on farms for 30 or more years. Chavez did not like illegals and made no secret of it. You will find most illegals in restaurant, construction and auto body shops and companies like Swift. For the person above that believes only Conservatives want cheap labor, Swift is a far left liberal.