Lauren Zanardelli and Graham Foster are the kind of customers the government needs to make Obamacare work. The chefs own and operate a bright orange hipster magnet called the Neue Southern Food Truck. The farm-to-table vehicle stands out in Greenville, South Carolina, even among the new gastropubs that dot the city's charming Main Street. Today Zanardelli and Foster are zooming around their rented kitchen on the edge of town, preparing deep-fried Brussels sprouts, Ramen with seaweed and pumpkin sweet rolls. They won't have time after their 12-hour work day to explore the new health insurance marketplaces that opened this morning,...