I don't know why this concept is so foreign to the people in my area. My favorite are the drivers I see enter the highway then immediately cross two lanes to get to the leftmost lane only to get passed on the right by the cars coming up behind them.
This is my second biggest driving pet peeve. My biggest is people who pull out from a side street right in front of me (often without stopping) when there is no one behind me and then proceed to go under the speed limit. Road rage ensues