The eastern EU border is 6000 km long and partially patrolled with drones (I'm not sure to what extent). The southern US border is around 3500 km long, and Mr. Trump has proposed to build a wall to reduce the number of people crossing.
In the debate surrounding the southern US border wall, why don't I hear much about the use of drones? I imagine that 350 drones in the air at any time should be reasonably effective at alerting local law enforcement of undocumented intrusions (10 km to patrol for each drone), but I've only heard Trump about using ancient technology (a wall) rather than modern technology (drones).
Has Mr. Trump or his administration published or otherwise described any evidence-based or otherwise informed (cost/benefit) analysis of a border wall, compared to other methods of policing the border, such as the methods employed by Frontex at the EU eastern border?
Related but different question: Why did many voters support a border wall instead of other border control methods?