Practically everyone knows about the second world war, but nothing is being done about rising fascism. It has nothing to do with not knowing, it's just stupidity.
There is no rising fascism in America, if people really knew anything about the Wiemar Republic, Republican Spain, or March on Rome they would know that the left always loses when it tried to be humane and gain power. The only time the left gains power is when 'tankies' are the ones leading the resistance.
If you need a good example, look at Germany. They have very strict laws about it and while there are still fascists there (as there are everywhere), they do not run the country.
Edit: On a more practical note, it's always baffled me how normalised it is. People who defend fascists in the US media are still respected and hired. They might be prominent political figures. Somehow calling attention to someone who is fascist is confused by anyone doing something as simple as saying "liberals are evil!", as if the two party system there has anything to do with racial supremacy. As an outsider, you look at it and think "This is the country that helped liberate Europe from the Nazis. How are they not ashamed?". Maybe I think the first step is allowing shame to enter into things when you think about your nation, instead of a quasi-religious patriotism.