In African culture it is considered rude not to properly greet first and ask the other person how they are.
Collakat, don't you mean "South African culture"? "Africa" is a pretty big place, with many different cultures.
And every culture has its own norms, which often they don't even fully articulate to themselves until people from somewhere else come along and violate them. For example, in France nobody expects or wants waitstaff or retail staff to ask complete strangers how they are, or wish them a nice day, still less ask them what plans they have for the weekend, heaven forbid! But if you walk into a smallish shop (i.e. not a supermarket) and don't greet everyone there, both staff and other customers, with 'Bonjour, m'sieurs-dames' ('Good day, ladies and gentlemen'), you are ill-mannered.
I do pick it up from our neighboring countries and friends from other (more north) African countries also. So that is why I said African as opposed to South African. However, we are seen as a friendly nation