After working in hospitality management for 12+ years, I can tell you that most hotels will say things like this, however when it comes to enforcing them, they are normally one of the first things to go. It becomes a "he said, she said" in determining what happened, and at the end of the day a hotel like the Mandarin is not going to want to upset its high $$ paying guests over something so trivial.
More and more hotels are going away from automated minibars, if not away from minibars all together.