tbh being captain is just extra duties like setting up practice with other teams and when you make a decision, you either have to force them to follow your orders (kano) or communicate to see your POV (karasu) to make them agree with your decision. In the end when it comes to the field (authority that matters more), the coach has the most power which can remove the captain from the field like with kano.
right now, the main reason why Kano wants Captain role is because it gets the most attention from media due to mandatory stuff.