Sure as hell ain't just Americans. Go anywhere these days and if there are people about then you will find the garbage. Still and all, that's the way we apparently are.
Reality is of course is that when there were half as many of us as there today, the amount of trash wasn't as obvious. Its only going to get worse as every day there are more and more of us.
“Give a man a fire and he's warm for a day, but set fire to him and he's warm for the rest of his life.” Terry Pratchett