The blessings of inter-state duty-free shopping

On my way home for Christmas I felt like doing my old man a favour and by him a bottle of Chivas Regal, his favourit whisky. In the airport shop the whisky shelf is filled with tempting goods, but no Chivas. I lift my head to see if there's more whisky to be found and in a distance, at the very far end of the liquor store at Brussels National Airport, hanging from the celing there's a sign with a Norwegian flag and a message stating, in Norwegian, that those flying to Norway still can enjoy duty-free shopping. Embarressed and with my head down in shame I walked over, picked up my father's whisky and got in line.
We're part of Schengen and we're part of the EU Inner Market, but we still have our own shelves at the airports equipped with big signs and arrows pointing us in the right direction.