The fear for unknowns plays a certain role in shaping the way you communicate with strangers. The curiosity for unknowns drives a motivation of scientists toward novel findings, whether or not it is merely an incremental. The ways, looking apparently different, seem to root in a nature, perhaps being genetically given, and appears so close to you when you walk in 'new' world both in geographic and/or in scientific contexts.
Salutation would be a good example, being recognized as vital greetings that firstly tell someone that you are not their enemy. You can observe people making salutations in any cultural group of human society, and even in animals, though in different ways of it. Seeing ones who getting in a way you are not familiar with, you tend to feel uncomfortable, and even become unfriendly to them. I could not help considering this tiny event as one possible origin of discriminations when a race faces to another race.
Nowadays, in developed societies, people are used to strangers. They know that a stranger could have different background, and what seems arrogant to you is not necessarily what he/she intended, but still they are not well set about how they can 'ice-break'. No matter how subtle a border between nations become, you'd better pay a certain consideration of this. It works in the same way when you start working in a new laboratory or a new company, as when you start living in a new country.
What is friendliness? This is almost equal to answering a question 'what's unfriendliness?” The way you find friendly/unfriendly is not necessarily the same as others judge friendly/unfriendly. This makes the problem even more complicated, making it farer from possible 'reconciliation'. When you stand a counter of Tim Hortons for the first time from Japan, you might be shocked in some way. That is OK. Take your time, have a deep breathe. You can think a bit more about it in retrospect on another day. What made you uncomfortable? What if you were in their position? What if you were in their position, and standing in front of an Asian who is not looking at your eyes and not making any salutations nor any instant conversations, and even throwing coins on the counter to ask you collect them? You could seldom understand that the one is new to this society, and grown in a society where people bend their bodies to one another instead of looking at eyes and shaking hands, having been taught that looking at other's eyes at first contact and handing coins/bills directly to other person are even arrogant, regards being silent in a public area as the top priority in terms of etiquette, etc.
A sensible person could find this occurring as they spent time in a new place, but, to be honest, it is still not perfect. Those who paying a special care regarding such potential conflicts could even oversee their 'arrogant-to-other' behaviors. What is tricky is that there is no clear cut 'surgery' to this problem, but, at least, you can minimize the risk of 'trespassing in bare feet' by your effort. It is the fear for unknowns that gives a rise to all the problems.