Never said that a wall helps them to hide. I said in previous posts that after they scale the wall, it's easy for them to hide in the bushes from BP agents if it's at night. I also stated that it is damn near impossible to hide from a drone.
So how many drones do you think it will take to do the job? How many miles of unprotected border do we have? How much will it cost to fuel, operate and maintain these drones? How many agents do we need to monitor what the drones see?
Infrared? Yes, they work great until the scoundrels figure out they need to cover themselves in an insulated blanket or perhaps a sleeping bag with holes cut at the bottom to stick their feet out. Or maybe wait until unfavorable weather conditions arise where the drones can't see them.
Well, considering that one drone can effectively patrol an area of 200 miles around it, probably 15 would do the trick.
How much unprotected border do we have? About 2,000 miles.
How much to fuel to run the drones? Dunno, might wanna check with the DOD for those stats (if they're not classified).
How many agents do we need to go after those spotted by the drones? Dunno, but I do know that the current BP agents on the border would be able to be used for much of it.
As far as hiding in a sleeping bag with your feet sticking out? Ifrared would STILL pick them up, even if it's just their feet. Hiding in a hole under an insulated blanket? Might work, at least until the blanket gets heated up and is spotted.
As far as flying in unfavorable weather conditions? Drones can fly in some pretty crappy weather, and if its bad enough to stop a drone, chances are extremely good the border hoppers won't be crossing either.