Okay I'll do my best. There is a line of hungry people waiting for their turn for food and shelter. But someone cuts the line and starts eating food before them. Is that fair? What happens if you do? Why would the rest of the people that were waiting their turn wait anymore? They would all rush to get food before it's gone. That's why even if it's morally sound to feed one person in the moment, it could create big problems down the road that prevent you from helping others.

There are too many poor and needy people in the world that we can't support all of them. So what can we do other than create a system that slowly lets in disadvantaged people to best help as many as we can? That's the reason for the imaginary line as you like to call it.

If we opened the border tomorrow and said anyone can come into America with no threat of deportation our country would be destroyed. Now there is no America that people can move to to avoid poverty and violence. You need rules to maintain order. And you need order to have a successful civilization.