OK so if YOU know this then Why did not the COP on the road right there with Shep or The Sate Police lady say "Just have them walk toward the Superdome?"
Sorry but your logic cuts both ways.
How do you know they didn't? Don't assume people are willing to follow directions. Especially people essentially suffering from a state of shock. People who refused to leave or go to a shelter in the first place. The simple FACT of the matter is that unless you are a blind mute, if you were in New Orleans today, and in sight of Shepard Smith, the Superdome was in your view and less than a block or two away. I don't know why people didn't go there. But I don't know why they didn't go there before the hurricane hit either. Sometimes it doesn't take direction from officials to take care of yourself. Sometimes you have to put your mind to it, put one foot in front of the other, and walk yourself to the center of the rescue effort in New Orleans. Or....you could just sit on a bridge abutment in the middle of an interstate and wait for the world to come to you.