This is a great question and one that can be best answered from a sociological and cultural point of view. Many differences emerge in ethics between people, because people are different. They are shaped by different values and customs based on where they live and their collective experiences. We can say that each part of the world has a different set of commonsense values. So, what is given in one society is not given in another. Let me offer a few examples to illustrate this point.
In America what is prized is self-assertiveness and individual accomplishment. Our ethics award this type of behavior. In Asian countries, this type of behavior is seen as boastful in a bad way. What is prized instead is teamwork. To stick out, in this society, is a social taboo.
Here is another example. In some societies, it is all about who you know. Relationships close deals. In other societies, it is all about merit.
Or to give another example, in some places in the world gift giving is a fact of life in business. There is no idea that gift giving is tantamount to a bribe, but in America, for instance, gift giving would be seen as a conflict of interest.
In conclusion, we all live in social worlds and they are not all the same.