Manufacturers put buttons on the left side of women's clothing as a practical means of distinguishing between men's and women's clothing. ... Since most people were right-handed, this made it easier for someone standing across from you to button your dress."

Why do some shirts button on the left?

To insure that an enemy's lance point would not slip between the plates, they overlapped from left to right, since it was standard fighting practice that the left side, protected by the shield, was turned toward the enemy. Thus, men's jackets button left to right even to the present day.

Why do men's clothes button on the right?

If you're wearing a men's shirt, the buttons are usually on the right. ... If you have a gun hidden in your shirt, it's easier to reach with the dominant hand. So if the buttons are on the right, you could theoretically slip your right hand into your shirt or jacket more easily.