Traditionally, men in the past were not as likely to wear a wedding band.
(When you think about it, it is less $'s to buy just a wedding band for the woman than to buy a set of his-hers bands for both of them. And back in the earlier half+ of the last century, it was not all that uncommon for the man to be the primary/only wage earner for a household, so saving the money wouldn't be illogical.)