Selling to the Poor

JULIAN WAINWRIGHT for TIME

FLOATING VENDOR: Nguyen Van Hon sells toiletries in remote, poor villages from his boat on the Ke Sat River in Vietnam

The floodplains of Soc Trang province in Vietnam's Mekong Delta are a maze of rivers and canals dotted with villages so impoverished that local farmers earn less than $1 a day. It is not an obvious place to seek a fortune, but capitalism finds a way. Steering his ramshackle boat along the Ke Sat River, Nguyen Van Hon operates a floating sundries distributorship.

The wooden hold of his boat is heavy with boxes containing small bars of Lifebuoy soap and single-use sachets of Sunsilk shampoo, which he sells to riverside shopkeepers for as little as 2.5 each. Hon's...