I thought it was because the authorities in charge of the evacuation really couldn't give a damn about that one-third when the 'Everyone for himself' evacuation order went out when the balloon went up. They couldn't even be bothered to organise any buses. The fact that after Hurricane Katrina passed though, the levees broke and New Orleans was flooded out then the armed road blocks went up around the city to stop those even attempting to get out by foot didn't help either.