Originally Posted by
Aisle Seat H
Of course they can when it is their word!
Euro is their term, for their currency, so they can decide how it should be pluralised !
Your argument implies that Apple should not be allowed to call a product iPhone or iPad because it is grammatically incorrect to have a capital 'P' in the middle of a sentence!
A better analogy would be that as the Italians own Rome and Venice we should be obliged to call them Roma and Venezia. It's their country after all....