I was thinking the same thing. Modern Japanese culture looks very negatively at people who put their own interests ahead of everybody else's, to an extent that you probably can't imagine if you haven't been there, and this is backed up by very low levels of inequality.
I remember a news program I was watching in our Japanese class in, uh, probably 1992. A couple of policemen were interviewing a distraught convenience-store clerk who had just been robbed.
"Did he look blue-collar, or white-collar, or what?"
"He just looked like a normal person! But obviously he wasn't, because he robbed the store!"
Our whole class (this was in the US) burst out laughing. The idea that, in order to commit armed robbery, a person would have to have some kind of mental abnormality — it was so alien to us as to be comical. That idea used to exist in US culture; Lombroso's theories used to be popular, eugenic policies were often justified on the basis that "morons" were likely to be criminals, and the word "crook" was a neat little package wrapping up the idea of mental abnormality causing lawbreaking. Much of Clarence Darrow's career was spent defending the most abhorrent criminals on the basis that their criminality was beyond their control, although not merely because of mental defects.
But, at least since the 1970s, an alternative conception of law and lawbreaking has been popular in the US — perhaps due to the absurd drug war, perhaps due to the discovery of abuses like the Tuskegee experiment, J. Edgar Hoover's campaigns of persecution against national heroes like MLK, and government deceptions about Vietnam and the dangers of fallout from open-air nuclear testing, perhaps due to the increasing cultural influence of Hollywood, or perhaps simply due to the failure of prosperity to be widely shared.
Whatever the cause, though, people from the US almost universally think of lawbreaking as a common and often harmless activity, not something limited to the mentally handicapped or partially insane — something that many people would do if the law weren't restraining them.
Also, in Japan, if you deviate from social norms, everyone will pressure you to conform. In the US, it's usually just the police.
Therefore the difference in looting behavior is unsurprising. I hypothesize that if you look back to 1955, you'll find natural disasters in the US with almost no looting, too.
Here in Argentina, things are even more American than in the US.
