Shanks is the most calm yonko he doesnt go against wg or his commnaders yet the rhp def have higher bounties than sweet commanders
Sure, that's a reasonable assumption, but the WG is going to be aware Big Mom is simply avoiding unwanted eyes at her fiefdom while Shanks remains a wildcard.
Big Mom is predictable insofar as being a business woman. She has an organisation to run. It's a role she takes seriously.
Shanks remains among the most mysterious individuals in the One Piece world, rivalling even the likes of the enigmatic Roger and Dragon. What little we do know of him is that he is
immensely powerful and will not hesitate to assert his strength, be it against other Emperors or the entirety of the Marine elites at Marineford.
I think it stands entirely to reason that Shanks' crew on average have higher bounties, even if Shanks has a lower one than Big Mom, by virtue - by my assumption - of the fact he does not operate some kind of territorial empire like Kaido and Big Mom and is more of an informal, gregarious, friend-making type like Luffy, WB and Roger.