A cultural difference I've noticed a lot between different places and regions and cultures is how important it is not to cause a nuisance or disruption to others, especially in public; versus if it's your responsibility to take care of yourself if you're being bothered. It's a very wide spectrum.
I saw this post on Tumblr that was like a long bulleted list of why you should always wear headphones when listening to music in public and I was struck by like, yes, I do value this too but I know for a fact that it's not valued by every culture.
I've encountered many cultures which value a sound of life and joy and not harshing other people's fun vibes over not being a nuisance. Where if you don't like the music someone is playing on a speaker on the bus it's you're responsibility to wear your own noise cancelling headphones or earplugs instead of making other people accomodate your own preferences.
Although, personally, I am absolutely of the belief that it's best to collectively act in ways which don't cause disruptions and nuisance on other people, I can see how this general attitude can stretch across a spectrum to various extremes.
In my head, the whole controversy around Sweden is a good example of this cultural difference. I read this article from a Swede defending how if a kid comes over unannounced near dinner, Swedish families don't feed the kid that's visiting. When Twitter and Tumblr learned about this it caused an international incident. But the Swedish logic was really just an extreme extension of the cultural axioms "don't disrupt the lives of others." The idea is that if a kid comes over before dinner spontaneously, then their own family might have their own dinner plans which would be disrupted by feeding their kid without their permission. What if that kid's parents doesn't want them to eat whatever you're having for dinner? What if the kid is full from your dinner and then they don't want to eat dinner with their own family and that upsets their parents? So to the Swedes, not feeding a kid who comes over spontaneously is "out of respect and courtesy for their parents." But to most other cultures, sharing food is seen as more important, and if a kid eats dinner twice, then Great! Feeding children is always a good thing. Especially if they're guests, since most cultures value feeding guests. Not all, it's like, idk 70%, but still a majority. The important misunderstanding was that Swedes do feed guests who they are expecting to be feeding. If both families know that the plan is for a kid to eat at another house, then they will! To many of us, we assume we will feed another family's kid and they will opt-out if they would prefer to save room for their own mapa's sålmonbrøt. But to the Swedes, the assumption is if that kid's family wanted them to eat your food they have opted-in by telling you in advance.
In my head, this is the "opt-in–opt-out cultural spectrum." And I think "music in public" is the perfect example. Where I grew up, you would only ever play music in public if it was in a designated area where music was expected and people who wanted to listen to it could opt-in to it. The only real exception I can think of is buskers at transit stations, but they need permits to do that. Whereas in Philly, it's very common for people to just play music wherever and if you don't like it you're expected to opt-out by going somewhere else or putting something in to block your own ears.
And this manifests in many cultures along this spectrum. In an extreme opt-in culture there can be a trend towards conformity. "The nail that sticks up is hammered down." You shouldn't dress in bright colors that distract other people. You shouldn't make things difficult for other people by being so different they can't understand you. You shouldn't speak up and disrupt the harmony of the room even if you disagree with what everyone around you is saying. There can be a tendency to value the appearance of harmony and peace while pushing problems under the carpet. In Boston, people are pretty polite and courteous on the train, but they can be hesitant to acknowledge the extreme segregation between white and Black neighborhoods. "It would make people uncomfortable to talk about that." Boston is also a low-context "Ask" culture, where people ask you things directly and expect you to say no, rather than a "Guess" culture where you don't ask the question until you think the answer will be Yes. So while, say, Japan and Boston are both opt-in cultures, Japan is still a Guess culture and Boston is still an Ask culture. "Opt-in" doesn't necessarily mean collectivist or high-context, it just means you value not causing a disturbance to others very highly.
At the same time as the aforementioned problems, this does result in quieter more peaceful and courteous public spaces. There's an increased desire to be polite to strangers and not stare at people who are different. There can be an attitude of "you're just trying to exist I'm just trying to exist let's just let each other do that without making it difficult." People might be very conscientious about littering and taking care of shared spaces. Greenery may be valued over athletic fields (which are too noisy) when designing public spaces. When people say "Japan is so clean" this is because "not leaving a mess for others to clean up" is highly valued. In Japan, teenagers clean the classrooms in their own high schools, and the club rooms they use for extracurriculars. You also get less noise pollution which is good for mental and physical health.
In Opt-Out cultures, it's your responsibility to take care of your own needs without expecting other people to change what they're doing to make you happy. This can result in some very noisy and stressful public spaces. Strangers will talk to you or even touch you assuming you'll tell them to go away if you don't wanna talk or he touched. People will start having parties and playing music and assume you'll just go elsewhere if you're bothered. That's your problem, not theirs. They're just trying to have a fun time. It also means people can be confrontational or less than precise in how they communicate displeasure. If you're stressed out and bothered then that's your problem. You need to take care of your own needs so you can be tough and handle being talked to about tough topics. It's not on them to soften their feelings and coddle you. This can make a lot of interactions harsh and intense.
But on the other hand, in this situation individuality is highly valued and so is diversity. If my hair or my gender presentation or my taste in music bothers you, that's a you problem. If I'm being gay and public and that bothers you, that's a you problem. Why should others conform to one person's expectations for their sake? It also means people are more comfortable speaking up when there's a problem. Being the outspoken dissenter in a room. Talking about things that make people uncomfortable. Even if they haven't fully formulated the most thoughtful or eloquent way to express themselves yet, they'll still tell you something is wrong and that is important. If we can't acknowledge problems we can't fix them. It also does result in public spaces that feel more "full of life." I have a friend from Philly who was living on a block that was very green and quiet and full of transplants from "opt-in" cultures who kept to themselves and tried not to make noise. At the time, I was living on a block which was very loud and most people were from Philly and had an "opt-out" mentality. When I visited their house, I expressed how much I liked their block because of how quiet it is. They said that they hated it and actually preferred my block. Because on my block there was always some kid's birthday party going on, or people hanging out on their porches playing music, and it just overall felt more alive and lived in and full of community. It's totally a matter of preference. I understand the appeal in a lively space like that, which is better created by an opt-out mentality where it's okay to make noise without everyone's approval, but as much as I tried to appreciate it I still ultimately prefer a quieter neighborhood where people try not to disturb their neighbors without advance warning, which is a natural outcome of an "opt in" culture.
I feel like this cultural difference isn't acknowledged enough as a cultural difference. People like me who prefer the peaceful opt-in attitude will just posture that this is objectively the civil and better way to be and characterize the opt-out way of things are unruly and uncivilized and something that needs to be fixed. Meanwhile the people who prefer the lively opt-out attitude will characterized the opt-in way of things as dead, depressing, weak, overly-sensitive, objectively inferior and undesirable, even morally objectionable. And both sides absolutely always see the other side as being a fundamentally selfish way to do things. Selfish to expect others to accommodate you. Selfish to expect others to tolerate you.
It we treat it as a cultural difference, maybe we can better find common ground and see it as not something with an objectively correct attitude. Just a matter of preference. Maybe seeing the positives and negatives of each will make it easier to appreciate why others have their own attitudes and how their way is OK too.