There's a reason, all right. When buttons began to be used on garments, it was logical that the the more dexterous right hand be used for the button. So buttons were placed on the right for men, whose garments buttoned at the front, as they could do the buttoning for themselves.
But in those days, womens' garments buttoned at the back, so someone else had to do the buttoning for them. It was sensible that this other person use their right hand on the buttons. For them to do this, the buttons had to be placed on the opposite side to the mens'.
As fashions changed, and womens' garments became buttoned at the front, it was still considered appropriate for a woman to have help in dressing, so the buttons remained on the opposite side to mens'.