A、It is the same in different countries. B、It is used to show American values. C、Its implication is sometimes misunderstood by v

Today there are many charitable organizations which specialize in helping the weary traveler. (26) Yet, the old tradition of hospitality to strangers is still very strong in the US, especially in the smaller cities and towns away from the busy tourist trails. "I was just  traveling through, got talking with this American, and pretty soon he invited me home for dinner—amazing." (27) Such observations reported by visitors to the US are not uncommon, but are not always understood properly. The casual friendliness of many Americans should be interpreted neither as superficial nor as artificial, but as the result of a historically developed cultural tradition.
     As is true of any developed society, in America a complex set of cultural signals, assumptions, and conventions underlies all social interrelationships. And, of course, speaking a language does not necessarily mean that someone understands social and cultural patterns. (28)Visitors who fail to "translate" cultural meanings properly often draw wrong conclusions.  For example, when an American uses the word "friend," the cultural implications of the word may be quite different from those it has in the visitor’s language and culture. It takes more than a brief encounter on a bus to distinguish between courteous convention and individual interest. Yet, being friendly is a virtue that many Americans value highly and expect from both neighbors and strangers.