I'm not sure where you are seeing that, the website says -
"During your time on board, you’re certain to receive our famous White Star service from all of our crew. Additionally, there are many more people behind the scenes supporting those who look after you directly. For your convenience, a Hotel and Dining charge will be automatically added to your on board account.
This charge, which varies for Grills and Britannia guests, will be shared amongst those crew members who helped provide and support your holiday experience, including the restaurant and accommodation staff, stateroom and buffet stewards and others. You can amend these charges any way you wish by contacting the Purser’s Office once on board.
For all bar and wine purchases, a 15% service charge is added to your account and this is shared amongst the beverage staff. A 12.5% salon service charge is passed directly to the crew member who has looked after you. This charge is also automatically added to your on board account.
Naturally, you are free to tip any member of the crew over and above these amounts, at your discretion."