Any equipment eventually fails. Designing it to fail safe- in a way that does not threaten the human operator- costs money. But a little warning message costs nothing and ensures that the human can be blamed when something goes wrong. The company can point to the message and say, "see, you should have known."

The message was never intended to help the human operator. It was intended to allow the company to avoid responsibility for cutting corners.

If the goal of the message was to communicate something important to the human operator, extraneous messages would be a serious problem. But if the goal is simply to cover the ass of the company, then extra error messages are not a problem at all. Thats why they never get fixed or pruned.