Like I said, use common sense for once in your life and you just might be able to grasp is.
Given that the game is about
Ninjas, it's obvious the rarity of the cards are based on both the person's status as a ninja and their power as a ninja. even the confirmed cards themselves show this :lol
I am pretty sure we can all agree being a Hokage trumps being a Hokage's wife, so when it comes to status as a ninja, Kakashi easily beats Hinata with that fact alone no questions asked.
And no, Hinata being a Hyuga means nothing in this regard as Shino too is from a noble family yet is C rank, clearly because he lost to 2-3 academy kids even with killing intent.
So why is Kakashi still SR while Hinata is SSR?
If Kakashi > Hinata in status AND power, why is he still below her? One of these most be wrong?
Unfortunately, Hinata is the one with Rikudo Chakra and ranked among legends
Never said she's on par, just in the same tier (SSR).