The scandal over the forcible removal of a passenger from an overbooked United Airlines flight from Chicago to Louisville, Ky. earlier this week promises to bring lessons on several fronts. It will of course compel United Airlines to review its policies on dealing with passengers on oversold flights, and critics hope it will spur a more humane response to such situations. But the incident also exposes the fact that airlines like United have little flexibility in handling unanticipated situations with shorter-haul flights, and they face pressures to maintain profit margins and cope with demand surges without commensurately expanding capacity. Public outrage has been swift, brutal and widespread since a video went viral of the eviction of David Dao, a physician. Seeing a marketplace backlash, investors also sold off shares of United Continental Holdings. It fell 3.4% in four days, wiping out nearly $1 billion in market cap.…