You're not the only one. Depending on how you met the Americans you've met, I wonder if it's a matter of self-selection. Speaking very broadly, many of the folk who subscribe to this stuff don't tend to wander very far outside their specific neighborhoods and circles; Canada isn't demonized nearly so much as Mexico, but they're both still "foreign" and therefore suspect (drug importation from Canada of course exempted!). I don't meet these people in person, though I know there are some in my city and even in my workplace ....