After getting used to driving in the US for a few years, it is a challenge to drive in India. Reasons are many – one has to unlearn the traffic rules learned here, get used to the stick shift, and figure out driving on the left all over again. In spite of the difficulties, I always like to drive myself — just can’t let go of the independence it gives.
I used to think that left side driving is just another sign of colonialism that the Britishers have left us, like cricket — and it used to make me feel bad. Until today, when I stumbled on one of the Yahoo! answers on the subject. Turns out, driving on the left does have its logic. In a detailed treatise on the subject, this site on World Standards tells us that
In the past, almost everybody travelled on the left side of the road because that was the most sensible option for feudal, violent societies. Since most people are right-handed, swordsmen preferred to keep to the left in order to have their right arm nearer to an opponent and their scabbard further from him. Moreover, it reduced the chance of the scabbard (worn on the left) hitting other people.
Furthermore, a right-handed person finds it easier to mount a horse from the left side of the horse, and it would be very difficult to do otherwise if wearing a sword (which would be worn on the left). It is safer to mount and dismount towards the side of the road, rather than in the middle of traffic, so if one mounts on the left, then the horse should be ridden on the left side of the road.
Right side driving, according to the site, came from France and with Napoleon’s conquests spread to other countries. For some reason the right side driving caught on in more countries, and today while only 74 countries drive on left, remaining 166 drive on the right. Population-wise, the left side driving countries have one-third of the world’s population, although it would be interesting to find out data on actual people driving in these countries versus those driving in right-driving countries.
It seems though, there are no contiguous countries driving on opposite sides of the road. Traffic between such countries would have caused quite some confusion.