The challenge on turn-based mode for this game is that after a player announces an action they are going to take, all other players have the chance to challenge that action. So, if playing a 1 move per day game and player 1 announces they are going to tax, it could be a full day before everyone agrees not to challenge that ability. This could cause the game to drag on.
I'm not saying this is an insurmountable challenge, but just a reason that the game (like a few others that are similar to it) disallows turn-based playing.