There were communication problems, especially between the current and former mayors of N O, and the Gov of LA. MS has more direct hurricane damage and are ahead of LA in recovery, they had better communication and didn't have the additional problems from the levee breaks. The Mayor said to evaccuate but many people believed if they made it through Camille they would be safe. The Army Corps of Eng already knew the levees wouldn't hold up to a class III or better hurricane, levees that were last updated in the 90's but basically unchanged since the last centuary, all levels of government gambled and spent the money elsewhere rather than upgrade the levee's or sock supplies. The (former) mayor was telling people to go to the convention center but none of the other officials knew this right away. Because cell phones didn't work and some of the EMS were knocked out within the city and state government no one told the Gov that people were in the Convention center. The Ambulance company had sattalite communications and began coordinating with the news services who could go out looking for news once the storm hit, that is how FEMA heard about the people at the Convention center, they already knew about the ones in the Superdome, but it still takes time to get the NG outfitted and deployed. Because FEMA is called by local governments, the local governments had to wait until after the hurricane hit before determining where help was needed.
The Gov of LA, only asked for approx 1200 national guard at first before the Levee's broke thinking they had missed the brunt of the hurricane which hit east of N O. Apparently because she lacked redundant communications she didn't know where all the rescue efforts were needed and what was needed, and no one knew how many had not evaccuated. When asked 3 days later she could not remember officially asking FEMA for help until after the news networks assessed the situation.
In the mean time the Marines and Coast Guard had amph vehicles, swift in the worst of the flooded areas and the boatmen of the bayou brought their flat bottomed boats in without being asked and began rescuing stranded residents, some of which remained in place as the water rose. They knew the area, wheras outsiders did not, this was given as a reason for perhaps turning away outside assistance, the same for helio so many in the air and no flight control besides sight, limiting rescue fliights to dayitme. Many people assisted where they were. No one expected a hurricane of such furry to make lanf fall on the East coast of FL and gaid strength passing over land to hit on the gulf coast, if the levee;s had not broke or if there had not been such a large storm surge, Cammile was only 22' as opposed to 19' for Katrina, many of the services provided by the infrastructure would have remained intact, once the levee's were breached, their fate was sealed.
I live in an area that flooded every winter, you learn to deal with it and are prepared for it, they were not prepared and the general population was not expecting it. It is no one person's fault. This covered huge geo areas.
I think we need to use it as a wake up call and make some simple peprations for suck desasters. On another thread I posted some of the things that can be planned for emergency survival.
The area was declared a federal desaster area prior to the hurricane landing, But they rely on the state giving specific request for services.