In markets, even illegal ones, we sometimes trust.
Seventy miles to the southeast in Quebec's Eastern Townships [DRH note: this is where my grandfather and grandmother grew up in the 1800s: my grandfather was born in 1855, my grandmother in 1875], a collection of roadhouses and dives known as "line houses" sprouted along the U.S. border. The tiny town of Abercorn, population three hundred, soon had five hotels catering to Americans arriving after a seventy-five-cent taxi ride from the train station in Richford, Vermont. The line houses branched into bootlegging as well. At Labounty's, a line house east of Abercorn in a hamlet called Highwater, young men from Vermont searching for legal booze also found lucrative work. Bootleggers hired the Vermonters to drive cars loaded with liquor seventy-five miles south to Barre. All were instructed to leave the cars in a designated garage, go for a walk, and return an hour later, when they'd find $125 waiting on the seat. The drivers never touched the goods or met anyone involved at the American end of the trip.
This is from Last Call: The Rise and Fall of Prohibition by Daniel Okrent.
What I find fascinating is that there was more trust than I expected. Obviously, a driver who, say, had been cheated out of his $125 could not go to the government. He broke the law and, besides, he wouldn't know the name of anyone in America to report to the government. So if they left, say, $25 on the seat, he would be upset but he would probably move on.