Yes it is hard. The slums of Mumbai are easy. Rio too. And Caracas. Lets do easy.

If there were free movement of people, maybe there would be fewer of those slums. Borders are just artificial constructs to keep the poor poor and the rich rich.

What makes the person who flat out sneaked in, violating the border laws with the intent of violating the laws and living here in violation of the laws, more deserving to be allowed to stay than those people waiting?

What makes the people playing in a corrupt system any more deserving? Besides, many of the people coming in from the South have a choice: immigrate, die in poverty, or get killed by some cartel asshats. Hell of a choice. I wonder what you’d do in their shoes?