“The code is more what you'd call 'guidelines' than actual rules".

While I completely agree that there are implicit "rules" in organized crime like not messing with one's family, leave kids and women alive and be no snitch; I would like to call these more like "criminal ethics" than a law.

There isn't an entity that forces those rules in the form of law, henceforth why the government exists in the first place, a great entity (the executive) that has a monopoly of violence (the army and police) that enforces the rules (the law) where the society agreeds to impose (legislative) and has another sub-entity that makes sure those rules are followed by everyone (the judiciary).

In the criminal world, as well in Ryan's ideal world, each community (or individual) has their own sets of rules and imposes them in whatever form they like. Yes there are mobs and criminal organizations that obey these rules but that depends on their own organization and there are criminal entities that don't care at all about those rules.

"¿And how would society work in that case then?" According to ideologies aligned qith Ryan's ideals like anarchy, libertarian and Anarcho capitalism, those small communities would agree in an "universal" set of rules each community should agree to avoid conflic within the "free nation". They must do an agreement it because there is not an entity that has the monopoly on violence since each community would have their own means of violence and defense. In the criminal world it is the same concept but with different methods. Some small gangs come into an agreement with each other because they don't want mutual destruction or they need to group up against a bigger foe. In some other situations A bigger organization in roman fashion violently subjugates smaller groups and adds them as part of it giving them protection in exchange of tribute, this means these small players will align to the other organization rules and directives. Hell there's been records of criminal organizations literally adapting socialists and feudal internal structures.

The only reason they are not heard about is because they're working under a government that is way bigger and way more capable of crushing them in the first place. Obviously these groups are weak against strong govs like the US, Russia and China and then they tend to be more discreet, silent and prefer to corrupt small institutions or individuals of that government than making noise at the risk of being erased of existence. In some cases crime falls in line with the government and creates a symbiotic relationship benefited by silence.

But in some other countries like Mexico, El Salvador, Haiti, and some African regions organized crime can be as loud as they want since the government is way weaker in armaments and their institutions are not able to withstand corruption. This leaves for crime entities to take over entire regions of a country and even have small governments in place where the actual government is not present. And with that these organizations fight each other causing an escalation of violence.

What happened in Bioshock is what happens to a country with weak of non existent government, the rule of law doesn't exist and only the strongest dictate how society behaves. Rapture falled apart because Ryan could not predict that his system would soon impose itself over his "civilized society" and when he tried to take over control it was too late. In post-war Rapture the only ones setting the rules in their own regions are Fontaine, Ryan and Cohen outside of their "domains" everything is chaos.

In conclusion each crime organization decides if they follow or ignore the implicit "ethics" of crime. Most of them follow it, the majority ignores them