Kathie, our small fire extinguishers are "adequate" for a small fire, like a grease fire on the stove. Once it's out of control, though, it's out of control... and most motorhomes/cars/trailers are melted frames on the ground in less than five minutes once they catch fire. A refrigerator
that already has the side of the unit involved, or a brake fire that has spread to the tire will likely not be put out by a small fire extinguisher.
Although it may not have been the case in this particular incident, unfortunately, many folks panic when they have an emergency and do nothing rather than take appropriate action... like use the fire extinguisher, or put a lid on the pan that has caught fire, or whatever. It's an old saw, but it's still true as ever... have plans for various emergencies and when you actually have an emergency, if you follow the plan, you'll likely do fine.