On the other hand - imagine you are a director at Pepsi managing this promotion. Imagine you personally sit down and send an email(or a courier-delivered letter I suppose) to the head of whatever factory is bottling your product, saying "under no circumstances print the number X on the bottle caps". Then the factory prints number X on 800k bottles.

Why is or should Pepsi be responsible for this? If I send an email to someone explicitly telling them not to do something, and they do it anyway - why should I be responsible for it? Unless the bottling factory is their own, but the article doesn't specify.