Though it's inhumane to think so, but unfortunately, this is a very common practice which is not just confined to Africa.
When the house is for all, then the chores in the house are for all as well. It has been a system for long that the male members will be the breadwinners, while the females will do the household activities. Now, though the time has changed, but that age old mentality is still hard to die. Ours is a male dominated society. Since the early stages of lives, boys are treated as the superior members of the family. Eventually, when they grow, they find it difficult to share household chores with their female counterparts.
However, things have changed to a large extent. Rather, now the role reversal is pretty rampant, especially in the urban households.