The economic philosophy which the majority of governments in the world adopt is liberalism. Liberalism supports free, unregulated markets and the avoidance of the intervention by the government in an industry that operates within that country. One of the consequences of Liberalism is that it has increased the gap between the rich and the poor. This is because the model favors individuals that already hold an important amount of resources and brings important limitations to the development of less favored populations. As a result of this, these populations tend to assemble and rise in protest against the current government and its policies.
In these nations the colonial empire did not leave the infrastructure necessary to prosper. The major piece of infrastructure was government. This led to wars and power struggles. The governments that eventually arose were often corrupt and favored a ruling elite who left the masses to starve. Communism is a workers movement which aims to promote equality and topple corrupt, elitist regimes. Therefore the starving people of these countries would find communism favorable to their current conditions.
There are several reasons why demilitarization was such an important part of the postwar program for Japan, but in general it was Japan had been extremely destructive for over a century.
"The boy in the striped pajamas" is a boy of the war time in Germany who only knows how to love and care for his friend. He is not bothered about the wire and the boundaries that separate him from his friend.