How is it implicit? The open parenthesis is before the function name rather than after, but the function isn’t called without both parentheses.
If you want to use commas, you can in Lisp dialects I’m familiar with—they’re optional because they’re treated as whitespace, but nothing is stopping you if you find them more readable!
Ancient LISP (caps deliberate) in fact had optional commas that were treated as whitespace. You can see this in the Lisp 1 Programmer's Manual (dated 1960).
This practice quickly disappeared though. (I don't have an exact time line about this.)
If you want to use commas, you can in Lisp dialects I’m familiar with—they’re optional because they’re treated as whitespace, but nothing is stopping you if you find them more readable!