Is the wall metal?
If so paint it black so it gets unbearably hot in the sun, then coat it with STP which will make it extremely slippery.
You do understand that the immigrants don't need to actually touch the wall. They use a ladder (all supplies provided by the paid coyotes at the border) for the 18' walls. They prop the ladder against the wall on the MX side, climb to the top, tie a rope to the ladder and let themselves down to the US side.
I've also seen video of coyotes driving a box truck, with a ladder and immigrants already on top of the truck. Makes for a shorter, quicker climb. Probably works especially well on the 30' walls.
This is a couple of methods for those who choose to go over the top. Others go under, and still others go through.
Yeah, that will work well 200 miles out in the desert where the fine, interstate quality highways will make it easy to get the box truck to the wall. Also, if using a ladder, they will enjoy that very comfortable half-inch wide ledge in which to perch while hauling a ladder up and over the wall.
Some of you people are incomparable dumbasses!
They don't need to haul the ladder over the wall! You kidder! All they have to do is tie the rope to the top of the ladder and let themselves down the rope. Only a dumbass would haul the ladder over the wall. I guess that makes them smarter than you. In your world would you pass the ladder back and forth over the wall for each person??
And fwiw, strong young Meemaw raper/killers do not go 200 miles into the desert to cross the border. They do it where it's easier to cross. And boy are they quick. Some cross back and forth on a regular basis.
I though it was those violent, killer rapers that were such a concern. You won't stop them with a wall. You'll only stop the old, sick, and poor. Are those the folks you are so afraid of?
PS. Have you ever driven in Mexico? They drive like mad, possessed people. They don't require fine interstate quality highways. Again, you are kidding.