Of course with arbitration all bets are off, but I've never understood how people in the entertainment business can get around the fact they signed a contract. I don't care if the contract says they will be chained to an oar 7 days a week until they die, it's a contract which they signed. Particularly since people in the business know that their employers will lie to their faces about what the deal is supposed to be and will then screw them to the wall in the fine print. The whole concept is that a modern society can only work if we can rely on promises made in business. If we can change the rules in the middle of the game, society will fall apart. Thus the importance of the enforceability of contracts. (Don't get me started on athletes wanting to renegotiate in the middle of their contracts.)
The only possible daylight I can see is if one party is required to be "fair" about something, and then isn't remotely. But again, it's the contract that both parties signed, and they had an opportunity to fix it up front and didn't, so presumably they want it just the way it is.