And people from Watch Hill come down to Emond's Field; thus, the knowledge would be telephoned along.
And fine, I corrected my language. She's no longer racist, she's bigoted. Happy?
Remember how they treated the Traveling People later in the series before they got to know them? It's not like Egwene is totally out there in her thinking in that scene. The whole of the Westlands are pretty bigoted to the Tuatha'an ... they are the only group that collectively has a derogatory name, akin to a racial slur in fact, "Tinkers" are pretty much universally disliked by everyone (the Aiel are too, but for obviously different reasons). Perrin's reaction is actually the more surprising one in the beginning, but his later contempt for the Tuatha'an is actually sad, especially when you consider how Egwene actually learns from meeting them and overcomes her initial prejudice.