Actually, people who like cues to make their subroutine calls easier to identify visually are unlikely to run into that problem, even if they weren't aware of the potential. Even though I don't use &, I never leave off the parens when calling a user-defined function (or method) with no arguments; the lack of parens screams "not a subroutine call" too loudly to me. I only rarely even make an exception for constants (and I wouldn't use & for constants, personally).

In any case, it is a trivial matter of informing the coder of that one simple fact to prevent that problem.