i think at "student age" when we're all relatively skint it should generally be halves. Of course, if the girl is like part time jobless, but wants to come out, i may offer to pay for us both, but on the whole i'd feel abit put off paying for a girl that isn't even my girlfriend yet. If she feels paying her halve isn't worth it for my company, then i dont really want to see her!
Sure you can argue its oldskool traditional for the gentleman to pay, but then i could argue in the same way stating its tradition for woman to stay home and do the cleaning cooking! But of course i don't, because i'm with the times!