Having driven all over the US and recently completed my ED, all I can say is that most American drivers are effing retarded.
My personal pet peeve are the a-holes who know there is an imminent lane merge coming and yet wait until the last possible second to merge and then try to force themselves into line. This causes more disruption to the flow of traffic and slows everyone down as everyone has to jam on the breaks. All so they can get some small smidgen of perceived advantage. Plus where I live (PHX) it seems like every one drives and enormous dooshy pick-up truck with massively oversized wheels that make 1980s caddies feel small on the road.