We are talking about metacurrency, that is why meta is the central oint here. If something is not meta, then it is not metacurrency. You may have not mentioned the word meta, it that is why I keep bringing it up to help bridge understanding.
Hit points are not a metacurrency, because they are not "meta", or beyond, the fiction. They are abstractions to mathematically model something within the fictional world.
Bennies in Savage World are not mathematical abstractions of something within the fiction, they are entirely outside of it.