Why are the buttons on men’s shirts and women’s blouses on opposite sides of the opening? Also, what about the zipper in the front of pants? Does the flap covering the zipper open on opposite sides in men’s and women’s pants?
With regard to the first part of your question, when buttons were first introduced, they were used primarily by women of means with servants. It was more convenient to place the buttons where a right-handed lady’s maid, who helped dress her mistress, could manipulate them. The practice stuck, but only in women’s clothes. The second part of your question stumped us, so we did our own in-house survey. We found that the zipper flap on all the men’s trousers opened to the right. The flap on the women’s pants sometimes opened to the right, sometimes to the left. It seems that with regard to zippers, all rules are off.