Comment by Delk
Depending on what "colder" means, some days it'll still be too warm outside, or some days it will be freezing, or both. Neither is good for many foods or drinks you keep in your fridge.
Of course this might still be micro-optimization from a rural Africa point of view. And a part of the reason for running the fridge is still just convention and convenience.
in rural plqces often they will also use alternate ways to keep things good besides keeping things cold, because its cheaper or more easily available than using a fridge. drying things, salting (pickle? not sure of the term sry) etc. so they have less usecases for a fridge than us (lazy?) ppl whi just throw a fridge at any such problem of food preservation