Fee-Fixing in Opera

The London blog Intermezzo reports on an article in Le Figaro discussing opera singer fees:

Fees are fixed by arrangement between the major opera houses like London, Paris and New York. The Met's Peter Gelb was quoted as saying that the directors are on the phone to each other all the time. Elisabeth Pezzino, director of programming at the Paris Opera, says that twice a year they all share a table listing what they've paid to each artist.

Does the FTC take an interest in these issues? Even major league baseball had to eventually give in on player salaries.