RCCL and many carnival boats have recently purchased their casinos from those outside companies. Vegas and the cruise ships are very different. Cruise ships do not want experienced gamblers. I have never lost money on a cruise ship. I know how to count cards and know basic blackjack strategy. The casino rarely watches for card counters unless they bet huge.
And when a casino sells their drinks figure if they charge $5 a drink they are profitting after the second drink of the bottle. BIG DIFFERENCE from AC/vegas/etc Cruise lines get everything duty free. Under $10 a bottle. If they give away liquor in a casino you will see people play for 5 mins just to get a drink