Including duty free??

I always thought the BP entitled you to purchase goods at duty free prices. My understanding is that all goods can be purchased regardless of destination but dual pricing is effectively in place and the boarding card allows for the cheaper (if applicable) price to be charged. You'll often see 'VAT free price' on labels. This is particularly noticeable for high tax items like cigarettes and other tabaco products.

In terms of staff training it's far easier to say 'scan the BP every time' than it is to expect a non tax accountant to understand the rules. This works for cigarettes but is clearly daft for Skittles. However, it is pretty accurate, simple to understand and cheap to implement.