Well, I do think they have haki
But Oda is too lazy to draw it sometimes...
He prefers to keep it vague... while he only focuses on drawing haki in details during the most important fights which decides the outcome of the arc, Luffy's fight in specific
Other fights may have those drawings if Oda was generous, and they may not depending on Oda
For example we know for sure Marco has haki since marineford... yet his clashes with King and Queen never showed black armament drawing
But Oda is too lazy to draw it sometimes...
He prefers to keep it vague... while he only focuses on drawing haki in details during the most important fights which decides the outcome of the arc, Luffy's fight in specific
Other fights may have those drawings if Oda was generous, and they may not depending on Oda
For example we know for sure Marco has haki since marineford... yet his clashes with King and Queen never showed black armament drawing