The Mekong river plays a central role in the lifestyle of the people of southern Vietnam. In the dark, boatmen load up their wares and start making their way up-river to meet with locals who come to buy wholesale fruits and vegetables on the water. Can Tho apparently has the largest floating wholesale market in the world! You can even get a drink of some strong Vietnamese coffee with a Banh mi (Vietnamese sandwich in a French style baguette) while bobbing up and down in your boat.
And this is how commerce concludes in the Mekong delta. I go out and meet my local farmer on the water (with my black but highly sugared coffee to go ;)) and the exchange happens right there. Unusual for some, but regular in Can Tho, Vietnam and most of SE Asia.