You can't just sack someone who is on contract, they still get paid, still get included in the salary cap etc, so it achieves nothing. The exemption is the NRL No Fault Stand Down, but that's not in play here.
The code of conduct is agreed to and signed off by all players, in fact the ones that I have been involved in are actually set by the players themselves at the start of each pre season. They agree to their personal and team targets, which includes a lot of stuff that the players themselves feel is important for THE TEAM as a whole. Not just them personally. Obviously they draw on the expertise of the coaching staff, but in the end it's the players that decide and then they often implement discipline appropriately.
It's not like doing your HSC, because that's YOUR HSC not the TEAMS HSC. If you fail the HSC it's only YOU that is affected, if you consistently fail to meet the code of conduct then the whole TEAM is affected.
Codes of conduct builds teams, bring the individuals closer together, solidifies the team, unites them in a common and personal goals, every day, every training session. All NRL teams have them these days.
We aren't talking petty shit here, it's usually serious stuff, repetitively. Not being 1 kg over your weight target, more like 10 kgs, not just once but week after week due to ignoring the nutritionists directives. It's not being a bit a slower (than your personal target) over the 4 kilometre run, it's more like not being able make the 4 kilometres at all. It's not missing 1 after training session with your goal kicking mentor, it's cancelling them totally. If you think that's harsh, I know Bellamy dropped a player last year for 2 games for not reviewing the videos of the games, he's a hard arse, but gets respect for it from the players.
Go Dogs
