Tbh I think there is about the same amount of retards in EU and NA. Fortunately many European tards from countries with a dominant native language(France, Germany, Russia, Italy) tend to stay below the radar in english forums because they just don't feel confident enough to troll/rage in english.
On the other side we get the full package from NA as well from European countries with a weak local language like the Benelux or Scandinavian countries. Unfortunatly the level of english is pretty high there - even among the feeble-minded. But in sum American idiots tend to surface more, while EU hides their gems in the local language forums.