Privacy and buying a beer

Sir, – Last week I passed through Shannon Airport. I attempted to purchase a €3 bottle of beer in the “duty free” shop where it had two prices displayed, one for travellers to non-EU destinations and a tax-inclusive price for those travelling within the EU. The cashier asked me for my boarding pass and when I asked him why, as I was paying the tax-inclusive price, he informed me that he was required by law to do so. When I declined to show my boarding card, citing privacy reasons, he informed me that he would be unable to sell me the beer. I did not witness anybody being asked for their boarding pass at the bar and I was not asked for it at the restaurant. What law requires me to give my name and destination to a commercial organisation just so I can purchase a bottle of beer? What is going on? – Yours, etc,

JACK BUTLER,

Meelick, Co Clare.