In the cases of Germany, Japan and other European countries post-WWII, I'd argue there were three factors: 1) An overt plan and programme to erase and supplant

In the cases of Germany, Japan and other European countries post-WWII, I'd argue there were three factors: 1) An overt plan and programme to erase and supplant the then present nationalistic cultures (particularly in Germany and Japan) 2) Military superiority and occupation 3) Gradual economic improvement, due to significant US aid and technical advice (the latter was particularly important for Japan) The first reason is the most important, and probably the most politically unfeasible now. You have to remember, WWII propaganda was intensely focused on de-humanising the enemy and de-legitimising their ideologies. The public would have been very supportive of efforts to stamp out Japanese and German culture, and 'give the savages' something better. https://en.wikipedia.org/wiki/Denazification https://en.wikipedia.org/wiki/Denazification https://en.wikipedia.org/wiki/Occupation_of_Japan https://en.wikipedia.org/wiki/Occupation_of_Japan https://en.wikipedia.org/wiki/Marshall_Plan#Effects_and_legacy https://en.wikipedia.org/wiki/Marshall_Plan#Effects_and_lega... 'On September 6, U.S. President Truman approved a document titled "US Initial Post-Surrender Policy for Japan".[10] The document set two main objectives for the occupation: (1) eliminating Japan's war potential and (2) turning Japan into a western style nation with pro-American orientation. Allied (primarily American) forces were set up to supervise the country, and "for eighty months following its surrender in 1945, Japan was at the mercy of an army of occupation, its people subject to foreign military control." At the head of the Occupation administration was General MacArthur who was technically supposed to defer to an advisory council set up by the Allied powers, but in practice did everything himself. As a result, this period was one of significant American influence, having been already identified in 1951, that "for six years the United States has had a free hand to experiment with Japan than any other country in Asia, or indeed in the entire world."' It should be noted that MacArthur pursued pretty humane and rational policies for the most part. Also, on the technical advice side, see: https://en.wikipedia.org/wiki/W._Edwards_Deming#Work_in_Japan https://en.wikipedia.org/wiki/W._Edwards_Deming#Work_in_Japa... . You can see the seeds of TQM or the 'Toyota Production System' in Deming's management philosophies.