I think, these countries, get second-hand, used furniture for free which is donated from other countries, or at very low price, so that's why the size is not suitable for them. From the Netherlands, lots of used computers are donated to African and some poor Asian countries. If you are still there, I would be interested to know about other furniture too; if you find some, do post about them.
Interesting post :)
My experience of furniture in many African countries is that tables and desks are high, and chairs are low - favouring people with long upper bodies. The other factor is that adjustable office chairs get "tired" after a while - I think they lose their gas. As for dumping? Not convinced. There are a lot of furniture shops in African cities and they sell newly (often locally) manufactured products. Appreciate your contribution, @monajam 😊😊