Sex for Money?

I had a friend in college who liked to call dates: "free food & free entertainment."

I just heard a woman complain that her 18-year old daughter is living with a young man and having sex with him but he is not giving her any money.  Sex for money - isn't that called prostitution?  Or is that a relationship?  The woman was appalled that her daughter's boyfriend responded to her daughter's request for money for a dress with: "Get a job."  Isn't that what a feminist would say?

Some women expect to be wined and dined in order to get laid.  Again, is that prostitution or a relationship?

What is the state of relationship politics these days?  Does a man always pay for dinner?  When is it okay to go dutch?  Is it ever okay for a woman to pay?

If a woman makes her own money, then can she have sex with whomever she wants - free dinner or not?

I had lunch with a woman who had been married for a very long time and was back on the dating scene.  She asked a mutual friend about the who-pays-for-dinner protocol.  The mutual friend was an attractive woman who said, "I've never paid for dinner."

I'm not sure what the underlying assumptions are and where they come from?

What are the modern rules and what is the modern rationale?