If the Taliban keep pouring in from Pakistan, why don't the Afghan and US armies simply build a border wall to slow them to a trickle?

You know about the wall that splits the West Bank from Israel? That keeps out the Palestinian insurgents from committing attacks on the other side.

Why shouldn’t Afghanistan take from their example and build a wall against Pakistan? The Taliban doesn’t have any air assets, so they can’t simply fly their militants over.

Wouldn’t walls and checkpoints that thoroughly check crossers effectively curtail the Taliban nuisance the same way the Palestinian one was in Israel?

I know there are already many Taliban in Afghanistan, but they keep getting reinforcements and armament replenishments from the other side of the border. A wall would weaken the Taliban already in Afghanistan.