Then again, as seen by the reactions of Reconstruction and the Jim Crow years tends to flag that people are slow to make any major changes in terms of social change. Consider that until 1962, children were actually forced to recite Protestant Christian prayers before class, and this was in public schools. This was the case even in cases wherein the person in question was Jewish or Catholic. Social change only comes through people challenging the social order, which often primarily comes during the onset and aftermath of war....Can we agree that this doesn't answer the question of how racism is defined or how it could be measured?
The anecdoctal argumentation provided in listing a series of US-centric events is hardly conclusion in any way to provide an argument that "only an world war can do this". Point in case, then the Great Migration was essentially driven by a labour shortage, which was accentuated by the world wars. But you could easily have other things drive up a labour shortage such as an economic boom, a government policy, changes in social attitudes or a pandemic for that matter. Where it gets silly is with the internment of Japanese-Americans, because on the face of it, the argument seems to be that the more a country will be putting minorities in camps, then the less racist that country will become. That is an obvious folly.
Another example, going back to World War II, women were expected to simply to raise children and were never expected to join the work force, even during the Great Depression. But when World War II was declared in the United States, the "Rosie the Riveter" movement was established, to deal with the manpower shortage, wherein millions of women joined the work force for the first time, and even joined the military for the first time. This planted the seeds for the Women's Rights movement, from Bela Abzugh to Betty Friedan to Rachel Carson (author of Silent Spring, which launched the environmentalist movement), providing opportunities from WPA Art Commissions to the WAC (Women's Air Corps).