From what I gather a number of factors. As one article puts it: "Social solidarity engendered by the wars, wartime experience of governing the economy, unemploy

From what I gather a number of factors. As one article puts it: "Social solidarity engendered by the wars, wartime experience of governing the economy, unemployment in the 1930s and the rise of socialist ideas." Both pension systems and labor unions were first created in the late 1880s/1890s and got a lot of steam in the early 1900s. Similarly with the modern iteration of minimum wages. Both the Nordic Model and Rhein Capitalism were created in the 1930s. On the more extreme spectrum, the Russian Revolution brought communism to Russia in 1917. In a way you can see this as the fruits of the critique of capitalism by Marx in the 1840s. They grew and took root in light of rising unsustainable inequality and lead to mostly positive reforms that brought down inequality even in societies that retained capitalism at the core. Then the trend reverses as the US starts their war on Socialism and Communism, and Reganomics and Thatcherism become dominant.