It's not that Americans are stupid, I'm pretty sure if this was run in other countries you'd see similar results. PEOPLE are stupid, and everyone has an opinion to voice whether or not they're educated on it.
That school shooting people seem to have no trouble glossing over the kid and his mother were apparently pretty crazy, she thought 2012 was real and all that good stuff.
But hey, rock and roll were at fault, violent movies were at fault, now it's games, whatever guess we'll just have to wait till holograms are around for them to get the blame next.