So summed up, its not a fair and consistent approach. It depends on who the captain is, their attitude and their nature, therefore, its not textbook good practise to approach captain, in short, it depends....
Its a variable. The captain has no special powers, at all, with regards the referee.
If anything the captain as per LOTG has some responsibility for the team.
if a captain cant see that, blue 5 is over stepping the mark, or cant tell that blue 8 is going to be dismissed for their next foul, then, that's their own problem. I know in Scotland, even from playing, if a ref called the captains in, the players would say "hey, its your job to control/manage the game".