I am Dutch, but this is just a silly rule which has nothing to do with local customs and traditions! This all just comes down to these people trying to be above and better and mainly to show that they can and more reasons to later increase airport security charges because of the "extra" security they have to take.
They use to do this rather often at CDG, but for my last few transfers over there, I have noticed this was not done anymore.

Furthermore, also at AMS, they have this obsession of asking you to remove your camera, open your laptop, etc.. I do wonder what is the purpose of this if you have invested so much money in your security equipments and yet still asking your paying passengers to have things removed.

I have never seen such "obsessions" in any other countries including the US and UK. Security is one thing, but being obsessive in trying to show the world you are much better is another.

Cheers!