The lowest price for a working second hand laptop in Uganda is about half a million ugandan shillings, which is about USD130. That gets you a 10 year old second hand model with minimum specs. If you want anything decent, expect to pay at least double. The difficulty of importing and the import taxes are at least part of the reason. In hindsight, sending the money would have saved a lot of trouble, but it would not have gotten him a better laptop than the one he received.

But otherwise you are right. Not only is it not economical, a lot of stuff that is sent to Africa is junk, and that's exactly the reason why Uganda generally does not allow importing of second hand products. On the other hand, i believe second hand imports are the only way to make laptops available at that price range. I don't know how that works though. Maybe they make exceptions for importers that they verify are not importing junk?