Taking group picture as a family is a very popular and important event in family. In Africa this picture is not complete without the family wearing the traditional Asoebi.
Cap is one part of Asoebi that complete the dress down. It can point out the ethnic group a family/person belongs to.
But not all Asoebi dressing needs Cap, scarf or any hair cover to match. Is also part of fashion to not use hair cover.
Asoebi is not always heavy, one can dress up very simple and fine. Most foreigner like it this way, but as African there is no particular choice.