I don't think locrian is all that common in spanish music (or any kind, for that matter.) While the b2 is common in spanish or flamenco music, the b5 is not, and often there is a n3 present, making phrygian or phrygian dominant a more appropriate choice for spanish sounding styles.
As for locrian, well its used to play over half diminished chords in jazz, not much else comes to mind. Maybe some metal players use it?