Individual countries like Greece have limited incentive to invest in controls insofar as refugees are only passing through. At the same time, unilateral action by countries, like Hungary, that are unprepared to countenance even transiting migrants, merely ends up diverting the flow.
讽刺的是，欧盟正是为了解决这种类型的危机而建立的。解决边境安全问题要求欧洲各国齐心协力。目前，希腊等个体国家没什么动力投资于边境控制，因为对它们来说，难民只是过境。与此同时，匈牙利等国家的单方面行动甚至连过境移民都不准备接受，其结果只是移民改变流动方向。