That's because code has documented and testable semantics whereas mathematical notation is more by convention than anything. It's in between natural language and code in terms of ambiguity, but is sufficiently flexible and clear to practitioners that it remains the best way to communicate to other practitioners.
...that's the thing actually: in programming syntax defines semantics because "syntax" is executed and in practice "it means what it does (what is executed)".
(Linguists would want to murder me for saying this, I know.)
That's why some programming languages can even be defined by implementation. (Though as a programmer I try my best to avoid these languages...)
