One possible reason that this is not the case is that natural languages and math have been around for a lot longer.
Another one is that programming languages have more in common with mechanisms that natural languages.
You could also say that we do have a few lingua franca programming languages which are also very similar to each other, to the point that someone fluent in one can easily read another.
Also, what do you think are the odds that a mathematician can understand the intricacies of a fluid engineering paper (in a natural language) and vice versa?
Another one is that programming languages have more in common with mechanisms that natural languages.
You could also say that we do have a few lingua franca programming languages which are also very similar to each other, to the point that someone fluent in one can easily read another.
Also, what do you think are the odds that a mathematician can understand the intricacies of a fluid engineering paper (in a natural language) and vice versa?