why left hand driving at different countries

cos some countries hav coaches las time with horses

Because it is hysterical watching americans look the wrong way and then step into traffic.

because some need to be driving on the ''right'' side of the road.

the rest are wrong.

This may help: >http://users.pandora.be/worldstandards/driving%20on%20the%20left.htm

Because most people r right handed.

Many years ago, british knights used to fight on horses, so they needed to be on the left to keep the weapon with the right hand facing the opponent.
On the first roads because of this, they guided their horses & carriages on the left.

Cars r better driven from the left because the shift is in the center, so it is more natural to drive on the right side of the road.
In many countries inside Europe, they used to drive on the left, but then changed to the right on the first decades of the 20th century, trying to unify the roads & use this more natural way to drive.

The United Kingdom, Japan & Australia r islands so they do not have the same need to unify roads, & that is why they r still driving on the left.