Actually, at the moment, they do. It's just over a year from the RWC, and the refs want the final. So, Barnes, Rolland et al are playing the political game and delivering what PO'B wants - or what they feel he wants. And the problem is, after the spray Dickinson got for reffing the scrums correctly when the Italians scrummaged like heroes - so slap-dash a spray that O'Braindead had to apologise to Dickheadson afterwards - the message has gone out that you don't piss off the ABs or you piss off Paddy - and if you do that, bang goes your golden whistle.
McCaw and Henry are more than cute enough to have worked this out and push it all the way. Good luck to them; that's their job. The problem is, the refs aren't doing theirs. But it doesn't help the ABs long-term, because in the RWC, the chances are they'll get someone pre-final who's not getting the final, doesn't give a shit and who'll ref it - and bin people - as he sees it. If the ABs get that when they've become used to the current, political, comfort zone, then they're in trouble. Take, for example, Garcés, a very good ref who doesn't give a shit who he offends; get him cracking down, and it will be a right shock to the system, because with him, a final warning means next penalty is in the bin, whoever it is.
Incidentally, the laws specifically require that after a player has been warned, he must be sent off or temporarily sent off for the next offence. Law 10 (3):
So, once McCaw was warned, he had to be binned for his next offence of any kind. Once the team was warned, the next AB penalised for that offence had to be binned. Didn't happen in either case.