There could be errors happening outside their control. Planes are sometimes rerouted to different countries for different reasons, but mainly weather-related. I've heard stories of travel agencies f**ing up travel planes because of wrong data, and people suing them because of unexcepted stops. Or the good old "they planned for Australia, but ended in Austria"-story. Happens far too often.. There are many targets where people confuse a city or country with a different target.