I spent about 6 months (on and off) working on the Gulf Coast following Katrina. (not New Orleans) The most common phrase I heard from the affected was "Thank You".
Indeed. You were working with individuals.
It's from a comedy ("Men In Black"), but a great quote is:
"A person is smart.
People are dumb, panicky, dangerous animals and you know it."
Look at any large group of people - be it Haitans, New Oleanders, people from Manhattan, or wherever. As a GROUP, things are going to start to fall apart after a huge disaster - mostly because that rare but vocal and active idiot will set things into motion that everyone else simply reacts to (and their action, taken individually, may even be the best thing for them - IE, if a crowd starts running/stampeding then it's a bad thing because people will get hurt - the crowd shouldn't do so, HOWEVER, the individual would be wise to move with the flow, else they be trampled or crushed).
This is simply the way the way the world works, because it's how PEOPLE work.