The main point though is that the "problem" of seasonal farm workers staying in the US illegally is to some extent artificially created by attempting to strictly enforce the border. Before that they were able to come work freely and would happily return to their home country because the process of getting into the US for the harvesting seasons was (relative to the modern process) easy, safe and cheap so there was no reason to stay in the US. Why would they, their wages would go farther in their home countries and that's where their families were and they would be able to cross back for the next major harvest they wanted to participate in.