Yorke explained the image as emblematic of exploitation, saying, "Someone's being sold something they don't really want, and someone's being friendly because they're trying to sell something.
She won the Nobel prize in economics for proving that these resources need not succumb to the so-called "tragedy of the commons" (exploitation by someone taking more than their share) if a system of checks and balances prevails.
At the time, a lot of people suggested it all smacked of exploitation, that someone somewhere had a financial interest in forcing a desperately ill woman to work, but Winehouse says the opposite was true.
But it is exploitation if somebody else is making a profit when they could afford to pay, and if your free work is denying someone else paid employment.
The Office of Children's Commissioner for England produced a report last year into child sexual exploitation entitled If only someone had listened.
Science: Most childhood sexual exploitation is done by someone the child knows, such as a blood relative, friend of the family, religious figure, or coach.
Like most countries, Britain subscribes to a UN definition of people-trafficking, the three-part gist of which is that the perpetrator must have recruited or transported someone, using coercion or deception of some sort, for the purpose of exploitation.
"But it's also an industry that traffics in exploitation, so it may make someone more attractive".
But there are rules, says Detective Sergeant Kim Gross with Toronto police's child exploitation unit, who argues that someone without training might screw up the evidence-gathering process needed to support a charge like luring or worse, tip off a would-be offender.
But Ms. Whitson of Human Rights Watch said, "That's what exploitation is — you take advantage of someone's desperation".
