A restaurant should certainly be diligent about giving clear, timely warning about hot plates. Not much excuse if they've treated such a safety issue lightly. I expect there are savings involved with the serving method: time. labor, water, etc.
One can burn their face, lips, and tongue at home, such as with a Hot Pocket, if not being mindful of the situation. Life might be safer just sitting in the middle of a bed eating a cheeseburger.