The thing is, this is a potentially sexist issue. As everybody knows, in the case of button shirts, men's shirts have the buttons on the right side and women's shirts have the buttons on the left side.
Therefore, I think some people might think that men's jackets would have the zipper car on the right side and women's jackets would have the zipper car on the left side.
No self-respecting guy wants people to think he is wearing a women's jacket. And, obviously, everybody pays close attention to which side of your jacket has the zipper car. Sort of like earrings.
