You can thank an entire century's worth of propaganda for that one. Every group in the United States that has asked for a better or more equitable society has been accused of being secretly communist / marxist / socialist / russian / chinese (those are all interchangable for Americans). And since neoliberalism has made the discussion of actual economic policy haram, people are left to only discuss the social policies (also due to the whitewashing that the State has successfully managed to pull off with regards to historical radicals).