In one of my postings on this topic I mentioned that the majority of
the world's population uses the decimal dot, not the comma. That's
true (since it's what the Chinese and the Indians do) but it was not
very clever considered as a rhetorical ploy since it's strictly
irrelevant to the matter at issue.
Suppose the Chinese were to switch to the decimal comma. That would,
I suppose, be enough to flip the world majority, but it would make
no difference to our question.
Here's the basic point: every programming language that I'm aware of
-- from low-level languages such as Fortran, C, C++ and Java, to
interpreted languages such as perl and python, to the scripting
languages of statistical software such as R, Stata, Eviews and our
hansl -- uses comma as the separator for function arguments (and
also as punctuation for other sorts of listings, such as matrix
subscripts). This absolutely rules out the use of comma as the
decimal separator or "radix point", on pain of fatal ambiguity; the
decimal dot is mandatory.
One may wish that things were otherwise, but this is just a brute
historical fact over which none of us has any control. Anyone who
aspires to computer literacy, regardless of the country in which
they live, has to come to terms with this fact.
In GUI entry boxes where plain numbers are wanted it's easy enough
to take ',' on input from the user and convert to '.' for internal
use, but when numbers appear in a context that involves functions
and other relatively complex syntactical constructs such translation
is not practicable. And neither is it practicable in scripts.