It's interesting to compare how different professions handle the ambiguity in left/right. In the maritime world they went with an approach at one extreme, where they just use two completely separate words, "port" and "starboard." (Though that's far from the only case where there's a special word for something on a boat.)
At the other extreme you have the medical profession where the first thing you learn in medical school is that left/right always refer to the patient's perspective. You could imagine that the maritime world could have gone with a similar convention. But the downside is that on very rare occasions someone along the way gets confused and the doctor operates on the wrong side of the body.
The theatrical world takes an intermediate approach, where they use the terms "stage left / stage right", which always refer to the perspective of an actor onstage facing the audience. Then the word "stage" tells you the perspective, but you still keep the words left/right so you don't have to memorize two completely separate words.
At the other extreme you have the medical profession where the first thing you learn in medical school is that left/right always refer to the patient's perspective. You could imagine that the maritime world could have gone with a similar convention. But the downside is that on very rare occasions someone along the way gets confused and the doctor operates on the wrong side of the body.
The theatrical world takes an intermediate approach, where they use the terms "stage left / stage right", which always refer to the perspective of an actor onstage facing the audience. Then the word "stage" tells you the perspective, but you still keep the words left/right so you don't have to memorize two completely separate words.