The tendency to associate the right with positive and the left with negative is pretty much ubiquitous in Western civilization up until fairly recently.
I have a fairly exotic viewpoint on this. The left/right asymmetry (for the lack of a better term) is a small part of a larger asymmetry that's difficult to explain (at least to my satisfaction): up is better than down, light is better than dark, positive is better than negative, higher human faculties are better than lower desires, right is better than left. In my mind, none of these should inherently have a good/bad association. Is a valley worse than a hill? Is a positive electric charge better than a negative one? But, for some reason we have this cultural, linguistic baggage where what seem like highly abstract objects are rooted in a very basic world of good and bad.
I find this fascinating.
I would go as far as to add the male/female asymmetry to this: seemingly senseless, yet historically present. I'd say the rabbit hole truly starts when you get into Western esotherics and see how they associate right, up, light, male, order, knowledge as if they're different expressions of the same thing, and analogously for left, down, dark, etc.
