Fires Burn in Space

In order for a fire to burn, there needs to be oxygen for the fire to consume. However, in lands observing this Law, that isn't true at all! Torches can be lit, campfires will burn, and explosions exist, even where there isn't any air to begin with, so it obviously doesn't consume oxygen to begin with.
Law originates from a bunch of movies that take place in space, but it can also be seen in StarBound, among other video games. Doesn't it explain how dungeons have lit torches even though no one's gone in them for centuries? They were lit all that time ago, that's how!