Marriages are too common for OOC reasons, I would say. But they aren't inherently OOC; it's plausible that two people would want to be 'permanently' bonded that way, and 'marriage' is the english word for it.
Sex I think is OOC, but you'll never sell that to the people or the PD. It's all a matter of what cantrian biology is like, which we can't properly tell.
I hardly think the idea of getting other people to do your work for you is an OOC one...
Code of conduct (as you mean it)...I've been figuring some of that comes with the language, which is imported in full from OOC. You may have some point there though.
Religion...look around. Do you actually subscribe to the theory that all real-world religeons were caused by divine interventions? Because otherwise there's nothing OOC about people piecing together belief systems from nothing. I have complaints (lots of them) about how it's often done, but not about the fact that it is.
If the complaint about fighting men is things like militaries automatically getting all "sir, yes, sir!", and pirates sliding toward pirate-speak (though I've never seen anyone actually go there) and things like that...yes, that looks a
lot OOC. If you mean the idea of people taking all those roles...soldier used to mean 'guy who caarries a weapon he doesn't own' in Cantr, now it's becoming a position logically derived from the tiredness system. Mercenary always made sense, though I doubt it's ever worked well. Piracy is obvious to anyone with a dishonest bone in their bodies the moment they see how a ship functions.
In my opinion, the only truly IC culture that exists has to do with random deaths and the sleeping disease, and the other player's interest for his character. Our chars look upon the death of other chars with much less compassion (except for the few respected community members that die) then, say, we do at the tsunami victims. They bury them (or not) and move on. Life is cheap (just hit the spawn button), so death is cheap too. We, the players, know that, and so the characters inevitably act upon that too.
I would contend that life is IC cheap for a number of reasons. One...no matter what you do, you see many many people die of the sleeping sickness. Mostly people who you only really notice because they clutter the ground where they fall, but a good thickening of people who've at least spoken a few times. Two, there is little culture of nationalism, humanism, whatever (naturally)...the biggest really cohesive IC groups would be small tribes IRL. You don't have any ties to the vast majority of people, so if they die, what should you feel but 'ooh, loot!'? Finally...people have been selling their lives cheaply for a very long time. The only deterrants to that are actual reasons to live...which many cantr characters don't have much of. If your life isn't that great, risking it isn't riking much.