Why swimming level is poor in the majority of third world countries?
The main reason is lack of means.
Indeed, Third World populations are generally reduced to the first needs of the Maslow pyramid. Physiological needs (hunger, thirst) and safety needs (job search). Therefore, it would be a waste of time and means for them to be interested in activity such as swimming. This disinterest will inevitably lead to a lack of qualified trainers.
A lack of qualified trainers leads to mediocrity.
Hence the training that lacks relevance depending on the level of each learner, not forgetting the methods of obsolete teaching.
Beside the lack of qualified trainers, most places have an absence or inadequacy of infrastructure.
Indeed, it is not always easy to have Olympic swimming pools, course materials to train efficiently.
So, to evolve into swimming in a third world country, you have to be a swimming enthusiast and it is imperative to have the means to live up to your passion.