Also road rage, lack of practical public transit options, the slap-on-the-wrist of most traffic offenses compared to other countries where it's much easier to lose your license / much more expensive to obtain a license in the first place, the lackadaisical attitude toward safety, especially w.r.t. Intoxicated operation, etc etc.
Isn't most of the States 55mph? (Serious question, that's the figure I remember from playing Road Rash as a kid)
In the UK the limit is 70mph, most of Europe is similar and Germany has no limit on the autobahn.