Could it be that:
1. Ghanaians can't write?
2. Ghanaians have no idea these contests exist?
3. Ghanaians don't have the supporting resources to enable them to contest for both the prestigious prizes (as mentioned earlier) and the lesser known (e.g. online) ones.
(notice I'm trying to be clever here with my use of Ghana's flag colours! Hit yourself if you didn't notice!)
I'm inclined to go with #3 although #2 is a possibility also. Ergo, we've got to do something about it and we are. First off, a writing contest!