They provide imposingly tangible evidence that something is being done about migration. High-tech surveillance and boots on the ground may be more effective at preventing people from crossing a border, but a wall can be used as a political prop.
然而，尽管事倍功半，但高墙仍是决策者和政客的最爱。高墙可以提供铁证，证明他们为移民问题做了些什么。高科技监控和荷枪实弹也许能更有效地阻止人们穿越边境，但高墙可以作为政治支撑。