Demand that they recognize. Businesses only recognize demand in narrow bands... if they don't sell eggplant, then they can't check to see how much eggplant is moving and increase supply of it. At best, they have to rely on business intelligence that 3 years after the entire country has gone eggplant wild "hey, maybe we should be selling eggplant too". In other words, they're completely blind to demand that doesn't rise to the level of "some fad or mania for this product has emerged".