I like the psychological and naturalistic theories of why this has been a societal norm. My first thought was that it was because women simply haven't had income for all that long. Going back, if the man didn't pay...you probably didn't go out.
If [insert activity here] was my idea, I often feel inclined to pay...provided I'm feeling flush.
If [insert activity here] was my idea, I often feel inclined to pay...provided I'm feeling flush.