This also gets into a whole debate of gender issues. For example in matters of HR, nobody is qualified to judge someone's gender. If this same logic was extended to bartenders and bouncers then "ladies' nights" would not be able to exist. Then again, in this case it seems that the state of the system is a steady state: (heterosexual) men are happy that women are at bars, women are happy to get cheap/free drinks and bar owners are happy to make money.