I would also like to see some deep trenches. The deep trenches would require tunnel diggers to go deeper. A wall is good, but I think we need some defense in depth. You would also think that with a decent road system behind the defenses you could have all sorts of robotic vehicles as scouts and first responders that could deploy non lethal weapons. Drones flying in drugs could be taken out by existing anti missile defense systems. A wall/defensive system can be very high tech.
The big thing that a wall does is that it makes the cost of human and drug trafficking more expensive and less efficient. If the traffickers have to spend time and money building elaborate tunnels and buying drones to fly over drugs, they will go out of business. This all drives up consumer costs and reduces demand.
South Korea has deployed Samsung SGR-1 armed robot sentries along the DMZ. They can identify targets up to two miles away.