B..
There is a different side for woman's button, because WAY back in the day...woman didn't dress themselves. Wealthy woman (and that's who clothes were made for) for as long as time began, did not dress themselves. It made it easier for someone dressing them, to have buttons on the opposite side. It's just always remained on that side. Now, they are just starting to make clothing differently, because woman have dressed themselves for so long...it just seems silly to have them on that side.