“”Sensors” and “towers” means no wall.”
It looks like they are stripping out as much of the costs as possible, into separate categories, to make the bill for the wall itself seem less.
The whole wall system, to work well in urban areas, needs a double barrier, with an alarmed no-man’s land (enforcement zone) in between, with lights and cameras so they can remotely see what they have to react to (e.g. armed or unarmed) and an all weather road for patrol and response. By splitting out the sensors, cameras, lights, roads and such, the remaining wall-only cost per mile will be a lot easier to sell. Even so, more than half of the request is just for barrier (wall or bollard).
Some of the technology spending, like sensors and drones, can much more quickly, and much more cheaply cover the broad stretches of rural and rough terrain - and effectively secure the whole border faster and cheaper.
The cost of the Wall is nothing compared to the cost of not having the Wall. This topic should be non-negotiable. If I were Trump, I would shut down the government for one week for every day that Congress fails to fund the Wall.
Recent reports are that illegal border crossings have already dropped by half since Trump’s election. Also, is Mexico going to pay for any of this???