The casino department and the retail department are separate within the cruise industry. Casino rates for sailings are different from retail rates and are not made public.
This is why you might qualify for a comped balcony on one sailing but only an inside cabin on another sailing even if both have similar retail prices. The reason is that casino rates are not the same for every sailing. Sometimes the casino rate is much lower than the retail price, and other times it can be very close to the retail price.
The casino can also create group blocks on certain sailings they want to promote more aggressively to players like you. Thus showing you better offers.