When I flew in this part of Africa for one of North Africa's best airlines, it was common for airliners, including my 727-200, to be greatly overloaded. I am not claiming that airline operators are deliberatley party to this dangerous practice, rather that they are not interested enough to actually do something about it. Typical overloading that I have witnessed is huge weights of hand luggage. One also wonders how much check-in luggage is counted as standard weights and how much understating of cargo weight occurrs.
I have also personally observed a pilot, who knew his aircraft was overloaded, take-off downwind on a hot day because it was convenient for his departure track. Instead of max take-off power on the brakes, a standing start from idle power showed disregard for the risk. Rotation at 10K below V1 was needed to get airborne in the remaining runway length. There is always the chance for out of range C of G under these circumstances as the load & balance calculations are a myth.
Space for baggage / cargo is the accepted limiting factor, not weight. An aircraft is considered just like a flying truck.
Of course this type of activity would need to be driven by corruption and we all all know there is no corruption in Africa.