Below is a simple graphic displaying what we see while driving. The left side A, displays the view of a driver on the right hand side of the road. The right side B, displays the view of a driver on the left hand side of the road.
As you can see, driving on the left side of the road is much safer, because the area covered by our dominant eye (the white area) is much greater than it would be if we were to drive on the right.