Re: Stayed at an overpriced Hotel recently and had a WTF moment:
Got back to find the door lock on the room had completely failed. You could just open it as if there was no lock there. Reason: low batteries...
There are two possible failure modes for this case, and neither is ideal.
The lock can fail to an unlocked state, which defeats it as a security measure. Or it can fail to a locked state, which could prevent an emergency responder from gaining access, or a parent from returning to a room with children in it, and so on.
You can debate the relative merits, but it's not clear that one is necessarily the better choice.