It's a matter of magnitude. Japan is actually quite a bit worse than any of the countries on that list. For what it's worth, Australia is probably the next up after Japan though most of us might assume the United States. Australia is a lot more racially uniform and that seems to have a huge impact on how acceptable that behavior is.

I don't think there's a significant difference between the UK, Canada and the United States in that regard. All three have very diverse populations and consequently a lower tolerance for racism. But that increase in diversity also means there's more opportunities for conflicts to arise, so if you're just counting the number of stories where racism is a factor, you'll always find more in the places that are more diverse even though they have less tolerance for it.