No, Sam, it was lack of planning, and the failure of the Governor and mayor to issue a manditory evacuation and utilize over 500 publicly owned buses that led to tens of thousands remaining in the city.
If you are suggesting that the government -- city, state, federal -- is responsible for evacuating everyone, you are asking for trouble. They haven't the resources, and if they did . . would you want to risk your life on it?
BTW, it's been discussed often on this forum that New Orleans did have an emergency plan in place which wasn't followed. Sometimes the best-laid plans get shunted aside in emergencies, unfortunately.