On the Song Exploder podcast, Take on Me episode, the artist talks about the producer saying that a male falsetto was a “make this song a hit” button…
There are not many tasks that can be cut-and-dried as universally "easy"/"hard". "The Star Spangled Banner" is a more challenging melody because of its wide range. Also, because it's often sung solo, with minimal accompaniment, to huge crowds.
If I were singing falsetto notes, I could probably launch into the range, but could I match pitch and harmonize without AutoTune?
I guess I could be biased because I find it easy and not everyone finds reinforced falsetto easy. But for example Bohemian's Rhapsody famous falsetto high note is Bb5, a full half-octave higher.