The school buses didn't belong to the school district, much less the city. These free-market idiots who believe in privatizing everything to make it more expensive and less efficient had ensured that there were no school buses available to move people. Nagin was an idiot, but that was one failure that can't be laid at his feet.
More disturbing to me was that Cuba had sent a ship full of doctors and Venezuela had sent a tanker full of fuel for hospital generators, and both were turned back by the Navy. Most of the hospitals stayed staffed by nurses and candy stripers (the doctors could afford to evacuate) until the All Clear, and the generators ran out of fuel until Halliburton trucks could get to them (even domestic trucks of donated fuel were turned back because only authorized vendors selling at elevated prices were allowed in).