We can close this thread, it's long now and people, rightly, don't read the previous comments.
After 90 comments, I understood that, perhaps based on the civilization of origin, on the anthropological process or more simply on the basis of one's individual character, for some groups of people greeting is a sign to express friendliness, for others it is a symptom of harassment, for still others it's simply unimportant.
It's good to know different approaches to social relationships. Thank you all.