They might not be paid more, but having built shift bids in the dark ages, it wasn't at all uncommon to have certain bid lines be restricted to language speakers, stair truck qualified agents, or seat control qualified agents. That also meant that someone relatively junior could wind up with a better shift than someone with a lot more seniority.
"Local policy will dictate" sometimes allows the company to play the "equal qualifications" card. Whether or not they choose to is another story. In MIA, I doubt they'd think twice about approving a CS between a non-Spanish speaker and a Spanish speaker. But they might think twice about their German, French, or Portugese speakers...
Some stations do the same thing with FSC's -- Crew Chiefs can work for a FSC, but unless they're D1 qual'd, they can't work for a CC. Others take the approach that a clerk is a clerk, regardless if he's a D1 or CC.