When we acquire a skill in a new language it is more than just putting words together. When you come in contact with new people, even in your own culture, you store information in your brain about how to deal with them: how they need to be greeted, how they like to go about doing things or what sets them on edge.
When we approach a different culture, a different language, a different country, we need to acquire the “ways of the land”. That is the way things are done in the particular place where the skill is going to be used. This is particularly important when learning to do things in English. It is truly a global language and that means that people will use English in environments where nobody is a native speaker. English and “how things are done” do not go automatically hand in hand.
One factor in this is the huge number of varieties of English: English has been nativized in many countries, like The Philipines, or Singapore. In other countries people do not use “English” strictly speaking, but creoles, local languages that have formed using English as their foundations – often because it was the language of the colonists – but including many local vocabulary and grammar items.
Try this easy experiment: if you live in a medium-sized or big city and use public transport – or even walking down the street – eavesdrop subsaharan immigrants when they are talking among themselves. Often they come from countries that used to be british colonies and they speak english-based creoles. (Or French-based creoles in some cases.
A second factor is what happens in countries like Spain where English is not a language people use in everyday life. The influence on English when it is spoken as a foreign language or a second language depends on the contact the speaker has had with an English speaking culture and also with whether the person or people spoken to are native speakers or second language speakers as well.
People who come from monolingual contexts – quite common in Spain – will feel their heads spinning by now. What is the protocol if nobody is a native speaker? It is not an easy issue. Even if there are native speakers, they could be in the minority. Usually native speakers are the most problematic in international environments, where they are just one more player in the game. In any case, common sense and politeness dictate that one should stick to the rules and customs of the host country. And of course, observe and adjust as you go. Again, common sense.
In conclusion, using English as a language for international communication is a matter of juggling with the different cultures, the origins of people and the location and situation where communication takes place. It requires an open mind, ready to not be shocked at anything – which doesn’t mean everything goes – and also ready to learn.