An opinion from someone who spent half of his life in asia and the other half in NA.
Read bold texts only if you hate essay.
I believe the answer is the way we are raised in NA. In other words, education.
**Most parents aren't dedicated to educate their children in strict&harsh manner for them to be polite, respectful, humble, and caring toward others. **
They do not lead them into creating comfortable environment for everyone. This doesn't show when they're young&simple minded, but once they reach teenage they show no hesitation to reveal the selfish nature of humanity, and once they reach adulthood the environment they create becomes one where if you don't speak up and act as aggressive as others you gain neither respect nor priviledge others get.
It also doesn't help that school takes little responsibility in that aspect.
Teachers are just there to relay knowledge. They hold no further responsibility than learning progress and well-being during class. It's very rare to see those willing to nurture students disregarding their own profit, and even then what they can do is very limited because they don't teach the same students for every subject every year.
In asia, every family raises children differently so I'll leave that out. School, however, is very different.
Homeroom teachers are stuck with the same students, teach majority of their subjects, and hold responsibility for their behavior until graduation. Teachers act as their 2nd parent and pyschological counsellors by maturing students' mentality and helping them with their interpersonal relationships ; more than often they approach students and their parents afterclass and pay home visits. They have to make sure nothing goes wrong within their classes or, as the adults who spend the most time with students, they're held responsible. By the end, students are implanted with the impression that they have to show consideration for everyone in their surrounding (class in this case) to create a harmonic environment and tend behave that way thereafter.
(Though students running into same faces all the time contributes significantly to their in-class affection)
P.S. While this may explain their behavior of showing consideration for others and expecting to be treated alike in return, it often causes problems when they do not get what they want because they're considered rude&greedy in their society if they speak their mind and have to wait for others to offer.
