That's not true. I sat here all day Sunday watching four lanes of traffic outbound and four lanes of no traffic whatsoever on a New Orleans freeway, I-10 I believe. It wasn't until close to dark that all lanes were outbound.
The president did in fact declare a state of emergency before the storm struck. Due some research. You'll find that to be true and he did it so the rescue and storm-aftermath logistics could be in place sooner. He also had to convince your governor and mayor to order a mandatory evacuation in the first place. Apparently your two local government officials hadn't thought of it or were unwilling to do it.
The people would not leave their homes. Do yo propose the mayor of New Orleans go door to door with a gun and force people out of their houses?
If that's what it takes to ensure their safety, in a word, yes. The Superdome and the Convention Center had thousands of people in them before the storm struck. If the people wouldn't leave their homes then who was at those two venues? There's a difference between "the people wouldn't leave their homes" and "the people couldn't leave their homes". Of course your logics say those school buses would have cluttered things. BTW if it was necessary for the mayor to go door to door with a gun then he obviously didn't convey the sad reality that could bestow these people prior to the storm's arrival, not only in the immediate future but months ahead. I don't know how things work in New Orleans but in the mid-90's we had massive flooding here in Northern California and our family personally had the Sheriff's Dept. tell us we had one hour to get out. One hour later they were back. Guess what. We left.
Your local government is every bit as responsible for what has happened as anybody else. That's the reality.