I didn't say we needed to track people as they move about the interior of the country. That would be ridiculous. But it is not too much to ask that we know who

I didn't say we needed to track people as they move about the interior of the country. That would be ridiculous. But it is not too much to ask that we know who is coming and going across the border. When I leave the country my passport is scanned. They know I have left. They know when I return. Think of it this way. You have a door on your house. When people come over, they knock on the door and you let them in at your discretion. You know who is in your house. But once in, you don't have to follow them all over as they use the bathroom or get a glass of water. You have certain amount of trust that they won't slip away and try on all your underwear. However, if they do, you probably would ask them to leave and might not open the door for them next time.