Sex for Sale: American Escort The world’s oldest profession is now a thriving black market economy, with an underground workforce that’s just an Internet connection and a phone call away. National Geographic’s Mariana van Zeller journeys to the heart of the American escort industry and uncovers the gritty reality behind the supply and demand of high-end sex work. Television has glamorised it and the internet has made it accessible,lity behind the supply and demand of high-end sex work. Television has glamorised it and the internet has made it accessible,