Well, first of all, I'm not Canadian. I've been there maybe two weeks in my whole life. I have friends from there because Taiwanese-Americans/Australians/Europeans all over the world tend to go to Taiwan during holidays.
I shouldn't have to listen to people talk shit about my friends because of the language they speak or the accent they speak it in. It's a common occurrence in Germany to hear young adults insult you in German after hearing you speak Chinese or English among friends, thinking that you don't understand the language. The children in Germany are even worse regarding their racism, but I guess children can be like that everywhere.
At least in the region that I'm living in, a plurality of people speak a foreign Asian language at home anyways, followed by English then Spanish. It's unthinkable for someone here to draw so many negative connotations just from hearing someone talk, and even more ridiculous for them to go ahead and insult them in English thinking that they don't understand it.
Death threats are not ok. No one should have to suffer those for even reasons that aren't inane and childish. Americans definitely make up most of the assholes on the subreddit, but they also make up most of the people. Honestly I used to have a pretty similar outlook on the US as you do, but once you actually live here for a while, it's really not that like the stereotype at all. In fact, a lot of Europeans on Reddit act more like the American stereotype than Americans do. That's not to say some stereotypes are true: Caucasians here are definitely much less fit than they are in Germany, people don't recycle well, standing in line seems to be a challenge for them, and they use way too much Styrofoam than they should. Donuts are cheaper than fruits, yet normal bread is still overpriced. School is unnecessarily expensive, there's way too much income inequality, I could go on for ages and I definitely prefer living in Europe over the US
That old ultra-nationalistic, ignorant, American-Centric stereotype seems pretty nonexistent outside young children and cold-war era adults though. On the other hand, European teenagers seem to be heading the other direction on these particular topics, especially in Germany with their rising role in Europe.