I learned to drive in California, back in the waning days of public school driver's education (classroom) and driver's training (behind the wheel. I did the classroom part at night school because it was a graduation requirement. I did the behind the wheel with my dad, who at the time was the district coordinator for the driver's training program and a certified instructor.
That mean that when we got in the family car so I could putter around he had a tendency to mash his right foot down, looking for the brake pedal that he had in the district cars. It also meant that I was taught by someone twice as neurotic about my driving.
The point of that: I had pounded into my head that the appropriate place for a car was to the far left of the lane. I was told that this was because the driver has the best view of things on that side and staying way over, close to the left line, means that anything you miss seeing because of the bilk of vehicle to your right shouldn't be much of a problem. As I drove up and down CA I saw that most drivers followed this most of the time, so I figured it was probable in the driver's handbook thing they pass out before you take your permit test.
Then I moved the Baltimore and had realized that they don't teach driving the same everywhere.
One of the benefits of extreme-left driving is that it leaves plenty of room for bikes (yes, this is a bike-related post after all). Here in Baltimore the tendency is to drive right down the middle or (when you see a bike) as far to the right as possible. I'm only slightly exaggerating there. On many occasions (including this morning's commute) I've seen cars that have passed me pulling so far over to the right that they end up in the bus/parking cutouts that only run part of the block and then have to slide back to the left to keep driving.
I suppose this is one way that the painted lines of a bike lane help - they create a "do not pass" mark for this kind of driver. I'd be happy if people would just stay to the left, the way I was taught.
(A big part of the dad-reminiscing is because yesterday was my dad's 66th birthday)