In a world where the Oda deliberately creates a Left Arm, calls both wings and even counterparts of each other, there is no point to have one having authority over the other.
If Oda is trying to resemble the dynamic we see in the Strawhat crew, which seems to be the case, then Zoro/Rayleigh and Sanji/Gaban can't order each other around because they only get actual orders from their captain, and if not, they just act by themselves without needing any lead, thats why it's called wings, they can be independant for 99% of the time.
In this case, we have 2 members that can assume the vice captain role. Even Nami sometimes looks like one, but she lacks the other necessary perks to fit the role.
If Oda is trying to resemble the dynamic we see in the Strawhat crew, which seems to be the case, then Zoro/Rayleigh and Sanji/Gaban can't order each other around because they only get actual orders from their captain, and if not, they just act by themselves without needing any lead, thats why it's called wings, they can be independant for 99% of the time.
In this case, we have 2 members that can assume the vice captain role. Even Nami sometimes looks like one, but she lacks the other necessary perks to fit the role.



