I don't like supermarkets in Africa

First of all, they are mostly only affordable to the well-off locals and rich expats; secondly, if the change that they should give back to you is too small, they always just keep it and make you take the loss.

For example today in Lagos, I bought a 1L bottle of juice for N245. I gave N500 to the cashier lady, but I was only given N250 back as change. When I asked about the N5, she just handed me a small candy (as if she was giving it to a begger) and said they didn't have N5 change. I was upset because firstly , as customer, why should I take the loss for their fault for not having small changes; and N5 can get me a 500ml sachet of drinking water on the streets. So I protested against the injustice and asked to return the juice and have my N500 back. I spoken loudly because I wanted to make a scene and to make people there see that this is NOT right. Maybe to other customers, N5, N10 or even N20 is no big deal and they are rich enough to "forget" it. Well, to me N5's monetary value is also very trivial. But I just really dislike this kind of practice! So in the end, I got my N5 back, and I will not go back to this supermarket again. I have encountered this same unpleasant practice in Ivory Coast as well. So are Africans really poor or rich?!