“How will such wall prevent a weighted line connected to a rope ladder from being tossed/shot from one side over to an accomplice on the other side?”
The main obstacle is just the sheer height of the wall, like a three story building. Testers had a hard time getting a grappling hook up to that height by hand, though it could be done. Another thing that testers experienced, was that somewhere between 16 and 20 feet, it started to get scary high for climbers. Thirty foot drops are more often fatal than not (those not killed, are badly injured, no walking it off). Non-commando men, women and children will be strongly deterred by the sheer height. It approaches a task for specialists, like rock climbers.
The other main deterrent to the rope ladder (or a regular ladder, with a rope to descend), is the kind of double barrier that is envisioned in urban areas - a no-man’s land between barriers, where there is no accomplice available on the other side, but rather a gauntlet of lights, cameras, sensors and Border Patrol.
Curve the wall towards Mexico. Now you are left dangling.