Why do women who pass the pencil test bother wearing bras?

If many women use the weight of their breast causing their back to hurt as a reason for wearing bras why don’t men with “moobs” have back pain and in need of a mra (man bra)? Are men’s backs stronger than women’s? Is a man’s physicality superior to women in that men don’t need support to hold up their mobs? And what of the women who are 36c or smaller who pass the pencil test, why are they wearing bras for? If they ain’t got no hang what do they need with that thang?