Members of Mexico's drug cartels are throwing grenades into U.S. consulates—so why aren't the groups designated as terrorist organizations? One reason, writes Malcolm Beith, is that they are not ideologically or politically motivated. "Their sole raison d'être is money." But recent attacks may make the U.S. reconsider the designation, as it is difficult to figure out which groups and individuals are motivated by financial gain, and which ones are motivated by political ideology.