I turned to the most knowledgeable person I know when it comes to leather and what I assumed was some kind of finish/top coat might not be that.
The leathers I have felt and used that I feel is a replica of the old apple leather cases actually have minimal finishing. So what is it then?
It is vegetable tanned leather where the leather has been fed certain oils during the very long tanning process which ends up saturating the leather. This creates a natural water resistance as well as a slower patina process, because it absorbs less of the oils from your hand and absorbs it slower. It ain't a thirsty leather that goes SLUUURP as soon as you touch it. Chrome tanned leather cannot be this way, the tanning process is way different and way way faster.
There can of course be vegetable tanned leather that has not been saturated, I have shoes in such leather (usually called crust leather, that is delivered uncoloured/offwhite and dyed later), so it ain't just about the tanning process but more so what goes on during the tanning.