Why not have the banker set the percentage that the ruler and other council members each receive? In this way, you create a possibility for tension between the Banker and Ruler. So, while the Ruler should technically be obeyed, if there is disagreement, they could swindle the ruler or simply not do exactly as the Ruler says. If however, the Ruler has full control, this possibility is eliminated.
Likewise, I recognize similar arguments could be made stating that a ruler not granting tax shares to some of their council members could cause conflict, but I see this as less such, because it will be automatically assumed that the Ruler as leader of the realm gets their say in what to do with taxes, should they specifically be given the game power.