I always wondered about person who orders hot coffee, then puts the Styrofoam cup between her knees, starts driving and then blames the store for not warning her it was hot after burning herself when she spilled it. Falls in the "can't fix stupid" bucket for me.
Oh, and she wasn't driving. She was the passenger in a parked car that her grandson was driving and had parked to allow her to fix her coffee.
The McDonald's version of the story that has become the version that most people know is that she was driving around and while in transport flung the lid open when it was held between her legs so she could add creamer and that is when the injury occurred. As you point out, she wasn't driving nor was the vehicle in transport. The same injury could have occurred while sitting at a table or desk, standing up, etc. In fact, it did. At the time of the lawsuit McDonald's alone had already had 700 reports of serious burns related to the temperature of the coffee. McDonald's ate it at trial because their witnesses acted like they didn't care that people were getting injured. That's why the jury awarded so much money. Her attorney was asking for $40,000 at trial.
McDonald's framed the legal issue in the public as a question of whether this old gal knew the coffee was hot and assumed the risk when she bought it. Well, obviously everybody knows coffee is hot. You know that just holding the cup. The legal addressed in the court was whether a company should be responsible for injuries caused by selling liquid at a temperature incapable of being safely consumed and causes third degree burns in seconds and selling that liquid in a flimsy styrofoam cup with an ill-fitted plastic lid, especially when they are serving them to people sitting in cars. In other words, is the combination of hot coffee, container and sales method creating an unreasonable risk of harm to consumers? If so, then McDonald's should be responsible for implementing a safer product. That is the legal analysis for product liability and that's why her attorney argued that the coffee should be served at a cooler temperature.