I do have it. On my keyboard - by default - there is “comma” on my numpad. (See animation below.)
Actually, the wording of the question is inaccurate.
The question - as the comment of @slbaumgartner suggesting - should be something like:
Why there is no “listing separator” next to the “decimal separator” on the numpad? 
Not exactly. You can influence it by regional settings, language and/or keyboard selection… 
(I’m on Windows but I assume Mac should have some similarities…)
