I am frankly confused by the 'wall at FRA' idea. Does the OP mean the semi opaque glass that one passes to enter the screening area? That is certainly not unique to FRA or to Germany.

But then does OP think that a terrorist is going to stand outside the screening area, observing, and use that information as the basis for an attack? More effective would be to target the very long lines which seem to form at US airports for screening. With waits of 45 minutes or over an hour, those lines are full of passengers in a very compressed area.

Allow screeners to focus on their zone? If you have professionals, they don't need a wall to do that. Where in the world does one see groups of screeners standing around, talking loudly, sometimes making inappropriate remarks, and generally chit chatting without paying attention to the screening area?

Building a wall isn't the solution. One has to fly exactly once to be able to observe the screening. TSA would be better to reduce the lines to levels found elsewhere.