You said we should arrest people who are not lawfully present as they are breaking the law. I pointed out that they are not committing a crime by merely being present. In order to prosecute somebody for a crime of illegally entering, whether that is climbing a border fence or something, they basically need to be caught doing it, or just after the fact. Some guy in the desert outside Ajo probably didn't come in on a tourist visa. Even then, they still need to prove you actually did it. Remember, people seeking asylum are not illegal immigrants. They are wanting to come here so they don't get murdered.