u drive on the left side of road => right hand drive
u drive on the right side of road => left hand drive
cos if driving on small roads, when you overtake the car in front,
u just need to peek out a little if RHD car, but if u drive LHD
car, your whole car have to go out to see whether there are
oncoming car towards you. (e.g. in singapore).
so if there is any oncoming car, you've already kissed when the
time you see, especially at high speeds.
most of the time, the advantage is not so obvious in singapore as
all roads are lane marked and wide. a lot of countries still have
nerrow roads where driving the wrong side driving cars are really
very dangerous. that is the reason of having two systems.
