Perl has fairly clear types like "scalar", "array", and "hash", so it could be useful for smart match to do different things when given an array or an array ref compared to when given a non-reference scalar. But even that case is not 100% clean (mostly due to overloading where you can have an object implemented as a reference to a hash that wants to behave like a scalar string or like a reference to a virtual array or such).

But you are very right when it comes to trying to distinguish between "number" and "string".

Smart match only looking at the "type" of one argument can improve the problem significantly. So I could see "when( 14 )" noticing that a literal number was given in the source code and so a numeric comparison should be used. But that clean line quickly becomes muddier in the face of code refactoring to things like "my $const = 14; ... when( $const )".

You either let that level of refactoring break smart match or you don't let smart match try to distinguish between strings and numbers (or else you doom smart match).

The only 100% clean case is having "when( @array )" behave differently than "when( $scalar )" (and similar).