My coworkers and neighbors have exactly the same advance warning of disaster and opportunity to prepare that I have. Warnings to prepare are plastered all over the buses and billboards in our county because we live in earthquake country, and expecting someone else to share their stash is NOT planning. Modern history (Nazi Germany, Rwanda, other places with societal breakdown) is full of stories of how quickly friends and neighbors will victimize others as soon as it is in their best interest to do so. I am not uncharitable, but I am not stupid either. Of course I would probably quietly share with persons I have an established relationship with and whose history with me holds promise of mutual assistance (a couple neighbors are construction professionals, another is just a darned upbeat person to have around).