It’s a common elemental theme we see across stories, fantasies, etc. It seems like it is an element that should be part of that pantheon but maybe there is a scientific explanation of why it isn’t? Or is it simply, they did not have enough understanding of it at the time those 4 were suggested.
Because electricity isn’t an element, it’s fairies. That’s why when there’s a short you see smoke: it’s really the fairies escaping the wires.