Because NO and LA are a corrupt cesspool. They had no plans, just look at this picture of the school buses unused that could have been used to evacuate 10's of thousands of people.
Since you mentioned highways I thought I would bring up an interesting point. I watched pictures of the traffic streaming out of NO the day before the hurricane and I saw that only the left two lanes were being used. The inbound lanes were still open to traffic heading into NO and there was very little of that.
In South Carolina all Interstate lanes are made one way to expedite the evacuation and no inbound traffic is allowed, even to the point of being arrested if you try it. I wonder why that wasn't done in La.
Shep Smith has reported that the population waiting at the convention center and on the overpass is PREVENTED from moving to Gretna, which is in another parrish, even though there is electricity there. People are being turned back even when on foot trying to leave.
Because NO and LA are a corrupt cesspool. They had no plans, just look at this picture of the school buses unused that could have been used to evacuate 10's of thousands of people.