I think you have to mitigate the situation by the fact that, with the water rising at the time, the food, if not removed quickly, may well have spoiled, so the option quickly becomes take it all or leave it to spoil.
Better it be recovered, and put to use, than left to spoil while people starve waiting for evacuation.
I believe Walmart said "take what you need" to the residents, since their inventory was a rightoff anyway.
I still don't go for that "take it before it spoils" - how do the various businesses account for it?
And it's not addressing the fact many are taking TONS of food at once.
In my Pollyanna mode, I believe for many people they're just 1 person taking alot for alot of people left at their apt complex or neighborhood roofs.