Most racists are dumb as shit. Not surprised that they keep making this same mistake.
Whilst Americans have the smartest people on earth they also have probably some of the dumbest most ignorant populations compared to all advanced world Countries (you just have to read this forum to see that

). I don't think i can name one person in the UK who does not know who Sikhs are. All my Sikh friends are some of the best guys i know, as usual they get the brunt of Muslim backlash - its a shame.