Tunnels? Ground penetrating radar. The BP already drags tires every day after the wall is erected they can just drag the radar.
Try purchasing, carrying, and using, a 30 foot ladder.
Especially using. If you’ve ever been up on one, it will scare the crap out of you.
Oh yeah, now you gotta drop on the other side.
It’s straw man argument stuff. And it doesn’t matter what they say, anyway. It’s going to be built!!!!