When you work and live amongst others, there are the written rules and the unwritten rules. The written rules are easy to decipher and discuss while the unwritten rules require some savvy and experience. I've never been that good at following the unwritten or unspoken rules of a group. I'm not exactly sure why this is true, but I know it's partly due to the combination of mindset, experience, mentors, and vision.
Those who have lived or worked with a same group for a long time, likely understand the unwritten rules well. They may also know the rationale and history for how those rules came to be, but for those joining the group for the first time, they may not know what to expect or how to act when it comes to the group's expectations, and that can create problems. Once I witnessed a scene like that where a newcomer acted far outside a group's norms--the newcomer was not embraced warmly because of this. In time, both sides came closer--the newcomer began to understand the unwritten rules and those who belonged to the group for a long time began to appreciate the spirit and strengths the newcomer brought to the group too.
When joining any group, it's good to take time to observe and learn about the unwritten rules. You may even want to study those rules a bit. Once I joined a group whose behavior, in part, seemed somewhat harmful, yet everyone acted that way. I found myself going along with the group without taking the time to think deeply about what I thought of that behavior or how I might react. Going along was not the right choice, instead I should have found a quiet, but positive way, to avoid the behaviors that were unhealthy--in time those behaviors did dissipate. I learned my lesson the hard way via a few tough errors.
When facing the quagmire of unwritten rules, I think it's good to be polite, honest, and curious. When I faced unwritten rules that were seemingly harmful, I could have explored the origins and rationale for that behavior more and made a more thoughtful choice. Also when the unwritten rules are questioned or misunderstood by newcomers, we can use that as a chance to revisit those rules with regard to the positivity or negativity they may bring to any group.
As much as possible I'm a fan of transparency for the rules groups adhere to--the more everyone understands what's going on, why, and the acceptable, positive ways to act, the better. Of course as we learn more, we have to update and revise the rules and routines groups adhere to. New knowledge mostly provides us with the opportunity to do better on our own and as a group.
If people in your group don't seem to adhere to the rules, written or unwritten, rather than chastise or ridicule those people, first take a look at those rules. Find out if the rules are clear, timely, and positive, and then, if needed, change the rules. If the rules are positive, then make the time to educate those who may not understand or agree with the rules. Listen as much as you speak during conversations like these. Onward.