Every function has its own workspace separate from the base workspace, and any variables in those function workspaces should be invisible to the outside world. That is the whole point of functions: a function encapsulates some functionality and provides a clearly specified input and output to utilize that functionality. For example, think of the mean function: do you know what internal variables it uses? Do you know their names or values? No, and there is no point in having these displayed, because the function is defined by its functional behavior, not by whatever internal variables are used to realize that functionality.
The only time that you should need to view the workspace of a function is when writing/debugging it, in which case you should use the correct tools for viewing that workspace, i.e. the debugging tools:
