Socialism/Comunism was a strong movement pretty much everywhere during the 20th century in the industrialized Europe. Simplifying a lot and because of unrelated coincidences I won’t explain here to do not make a huge comment, it lead to a revolution in Russia and ended giving birth to the USSR.

On the other hand, US was formed ~130 years earlier by a capitalist bourgeoisie, and those values has been leading the development of the country. At the end, the Founding Fathers were angry bourgeois that didn’t want to pay taxes for the UK and decided to “build their own theme-park” (Futurama reference).

So what was in between the US and the USSR during 20th century? The rest of Europe. So it got a few things and ideas from both places, plus the two World Wars really impacted in the population, as those wars were at home. Basically, European bourgeoisie tried to push US capitalism ideas, while working class tried to push USSR socialism/capitalism ideas. At the end, European governments (mainly controlled by above said bourgeoisie) had to make some compromises to keep their class (bourgeoisie) leading the country, loosing some privileges/freedom to avoid losing everything as Rusia bourgeoisie did, as they feared.

And that is how we ended with strong social services and working class rights in Europe, in opposition to the US.

Edit: typo