Why do we yield to the right and not the left?
For example, say you have a 4-way stop and these two vehicles stop at the same time, and both want to go straight.
The answer is: if we yield to the right, it clears the intersection faster than if we yield to the left. In many circumstances, you do not need to wait until the other car is gone into the far distance, disappearing over the horizon, and the dust settling on the ground before you start to roll; you should start rolling when the other vehicle is pretty much out of your way. This is all based on the idea that the point of driving is to get somewhere (I think!) and clearing intersections in the most efficient manner possible would benefit everyone.
If Car A goes first (the car on the Right), then Car B can start rolling when Car A is about half way through the intersection:
If Car B went first (the car on the Left), then Car A would have to wait until Car B got across the entire intersection, remaining fully stopped, and then could proceed. This would take longer (especially when the roads are very wide).
Is this making any sense?
If you are car B in this case, DO start rolling once car A is half way across. (Don’t give the other driver a heart attack, but do be assertive.) This will make it clear to vehicles arriving after you that you intend to go. If you stay completely stopped for longer than necessary, other drivers may become confused.
For more info about 4-way stops, see: 4-Way Stops
For more info about 2-way stops, see: 2-way stops: Why stop behind the white line?