In any instance, it takes a few disgruntled, enterprising people to start a riot or mass vandalism. Particularly the disaffected.
Racial homogeneity can only go so far to explain things, but Japan is a country where people generally look out for one another. When I was there, people were so polite that I thought these people were feigning politeness. I remembered walking out of a food stall when the head waiter would call out that a customer is leaving, and all the wait staff would turn around and bow and ask us to come again. It was simply amazing. I guess by learning to be polite even when you are tired, stressed, you become very good at being outwardly calm and it helps to maintain social order.
Incidentally, I remembered the caning incident where a young expat in Singapore spray painted cars and got several strokes of cane as a punishment. Wanton destruction is an alien concept to me when I grew up in Asia. A lot of vandalism with spray painting were simply copy cats importing an unwanted culture.