"To take a very prominent and obvious example, most people want to have sex, but the amount most people are willing to straight up pay for sex is around $0."
That's a bad example. There's ways to "pay" for sex other than just handing cash directly to the "other participant". In fact, most sex probably is not "free", if analyzed sufficiently carefully. Even if we count the monetary value of time at zero.
Similarly, customers appear to be unwilling to pay more for the face value of the ticket, which is why airlines are trying to make up revenue on other "extras": baggage, meals, extra leg room, etc.
That's a bad example. There's ways to "pay" for sex other than just handing cash directly to the "other participant". In fact, most sex probably is not "free", if analyzed sufficiently carefully. Even if we count the monetary value of time at zero.