If you are a regular traveler abroad, you must surely have noticed that while some countries have left-hand drive, there are others with right hand drive. We often take the rules of our home country as granted and compare it with those in other countries. For instance, India is a left-hand drive country but if you go to several countries in middle east, most of the countries in Africa, Europe and America, you will find the right-hand driving system prevailing. In fact, apart from the Commonwealth countries, which saw the rule of Great Britain at one time or another, most of the countries in the world are right-hand driving countries.
Why the difference? Evidence shows that from time immemorial, people used to walk or ride on the left side. Chief reason was the right-hand dominance in most people. It was in the right hand that most people held their swords. Handshake with the right hand became a norm because it was symbolic that you were not holding any weapon. Even while hitting a person; it is always easier to hit the opponent on the right than on the left. These were the chief reasons which contributed to the left-hand ride become predominant in medieval period. It provided the safety to the horse-riders as it was advantageous for riders while riding on the left side of the ride, as it kept their weapon hand free to hold a weapon or even to give a friendly wave.
Driving on the right side got prominence much for the same reasons people drove on the left. With time there were lesser people driving a single horse or carrying a sword. With two or more horses in a chariot or coach, it was easier for the driver to reach out to all the horses with his stick or whip while sitting on the extreme left rather than on extreme right. Moreover, with time people began to carry guns instead of swords, bows and arrows. At times there were no driver’s seat at all in wagons and the driver rode on one of the horses in the team. In that case, it was much more comfortable to reach the most horses in the team from the left-rear horse. When wagons of these kinds passed each other, it was to their advantage that they be on the right side of the road, as they were on the left side of the wagon and could easily make sure the wagons were not inadvertently coming into contact as they passed. This was one of the chief reasons why countries like US switched to right hand drive.
But the chief reason right hand drive became a norm in Europe was the rule of Napoleon Bonaparte. As he conquered more and more countries in mainland Europe, Bonaparte saw to it that the French laws were followed. One such law mandated right-side driving. After two-decades of right-side driving, mainland Europe continued with it even when Bonaparte was no more.
With time we find that it is the right-side driving that dominates the world. England never came under the rule of Bonarparte and hence continued with left-hand drive. It is this reason why countries, including India, that are part of the Commonwealth, continue to practice left-hand drive.
Normally, it isn’t a problem driving in your mother-country as you are habitual of the side – be it left or right. The problem arises when you are frequent traveler or when you drive past the border of one country to other which has the other system in common. Driving from Macau (left-side driving) to China (right-side driving) or back is therefore always a problem as it becomes difficult to change the driving side at borders. The same is the case with Thailand (left-side driving) and Myanmar (right-side driving). The problem is so acute that Thailand was even considering changing to right-side driving but has not taken the decision yet keeping the benefits were expenses of adopting globally-dominant right-side driving system in mind.