As someone in computational physics, let me assure you it's the same there. The one thing is doing math right and having the correct idea about coordinates. The other is being able to tell the computer about these ideas! Many people cannot code, so are not aware of array or vector facilities of their programming language/ecosystem they use (or rather have to use, because it's always have been like that).

This Phd comic is pretty acurate about the situation: http://phdcomics.com/comics.php?f=1689

Now imagine being a newcomer with neither programming experience nor domain specific knowledge and asked to add some feature to such a legacy codebase. This is the standard case in science.