MIAMI — Tony Haber had grabbed a six-pack of Mi Cristal beer at a Latin grocery store in Miami when an older customer in line pointed at his purchase and scolded him. The beer in his hand, Mi Cristal, was owned by the Cuban government, the man insisted. And he yelled at Haber with increasing ferocity that he was propping up Cuba’s communist regime with his purchase. Customers turned to watch. The cashier froze. Haber had no choice but to leave the beer and hurry out of the store. He did it even though he knew something the customer didn’t: The beer he was buying was his own. Haber is the owner...