You are right it's in >99% of the cases redundant.

IMHO it doesn't really matter what other cases are, what matters is that they are extremely rare.

That's why another approach is sorting with "key functions", which is not only shorter but also faster.

tldr

For a deeper understanding it's worth looking over the fence.

Python (among other languages) has key functions and Salva implemented them with Sort::Key.

But why does Salva's implementation provide a zoo of different functions making it more difficult to grasp?

Because comparisons in Perl are operator based while Python is typed based. (There is no eq in Python, a value is a string or not)

Hence Salva needs to implement keysort nkeysort to reflect the differences between == and eq ... In Python they rely on the implicit type.

And he needs rkeysort rnkeysort to reverse the sort order.

IMHO

A perfect solution in Perl would involve an additional Sort::Key like solution, with a syntax reusing the established operators cmp and <=> plus an easy way to indicate reversing the sort order.