Then the user has the choice to call earthDistance to get the program's preferred estimate of distance, or haversineDistance if they want to be certain about the implementation. Later, perhaps you add a new distance formula and earthDistance decides which method to use as appropriate.
Feels like the difference between inlining quicksort vs. calling quicksort() vs. calling sort(). In some situations you really are on a level where you need to know you are calling mergesort() and not quicksort() but some are fine with sort(). I doubt there are many examples of code I'd argue for inlining.
