And how about a few stationary dedicated satellite and a hundred blackhawks loaded with troops 24 hours a day. Since Mexico is paying the bill, the sky is the limit, right.Exactly if they found 80 tunnels be assured there's plenty more along the border that they haven't found. A 1000 mile wall will produce 1000 holes and tunnels underneath the wall.
That's what ground-penetrating radar, motion and geological sensors, and other technological capabilities are designed to locate. The Mexicans would have to build hundreds, if not thousands of feet down, to avoid being detected, which is extremely dangerous.
Keep in mind that much of the billion dollars in technology in use today isn't working. What might be a drug smuggler or a migrant, all too often turns out to be a cow, or the wind, or some other false alarm, which may be why the agents seem to pay the constant beeps from intrusion alarms little mind.