I live in a college town of around 100,000 people about half an hour outside Oklahoma City -- well over a million people in the metro area. I have to say that drivers in my town and on the country roads where I ride are on the whole cautious and courteous. Of course there's the occasional exception. On the other hand, I do not ride in Oklahoma City except on a handful of bike paths that are separate from the roads. I find it hard to believe that people twenty miles away are significantly meaner, less disciplined or more stupid. However, Oklahoma City lacks the infrastructure, signage and general bike awareness of the college town where I live. Apart from the random distribution of a-holes pretty much anywhere, the built environment can make for bike-unfriendly drivers.
Before moving here I lived in Italy for 23 years. As a rule drivers there drive a lot faster in any given setting, but also show a much greater degree of situational awareness and car handling skills than the average American driver. That doesn't mean it's perfectly safe though. Two people I knew were hit and killed while riding near where I lived.