To Americans, this is foreign territory. We look out for ourselves so much--too much. To the Japanese, there is a great sense of unity and being part of a bigger whole. You take care of your neighbors as well as yourself. You don't jump ship. This is why, when they have a disaster like this, no one loots businesses or steals from another or takes advantage of another person in any way.
When one does "jump ship," he is dishonored, even if leaving is the only option for your safety and the safety of your family. It is a harsh judgment these people place on each other, but it is part of who they are and how they live.
In most circumstances, it is a wonderful way to live--so tied to the good and benefit of those around you, but this is a hard situation compounded by this way of thinking.