Garth Brooks has a (smaller) following around the world. Which surprised me, too, to be honest. But it's there. You may be right about Kenny Loggins. When I read "Kenny who?" my first thought was Kenny G, who actually does sell quite a few records overseas, but then I looked up and saw who it was.
If this list was made international I strongly doubt the statistics would change much, if at all. Outside of the US and Japan music isn't sold as much. In the past this had to do with economics and now it's mostly about easy piracy. Also, the American market has always been so much bigger until recently. And they tend to become popular internationally while many others are only popular in one region. If someone was huge in China or Japan they might manage to outsell one of these artists. X is a more popular letter in China, as well.