I'm from the UK and this isn't too much of an issue beyond the couple of usual idiots. Went to the US though and it was insane, we were getting overtaken by school busses going 95. We were at the speed limit and getting overtaken by almost everything.
...when the speed limit's 85 it's pretty normal for traffic to move at 95; rule of thumb is less than ten over on highways and less than five over on surface streets...