Just so you know (and since you have been on 2-3 cruises, you should), Cruise lines have been charging for soda products for years! Not sure when your last cruise was. The auto-gratuities are based on per person, not per group and you always have the option of disputing the charges if you feel you received less than good service. Your tip about "bring sodas" will not help as the cruise line will confiscate them when you board the ship.
Review by Motherof4
In response to review, CrusinTim says ...
Yes, you have to add in the costs for sodas and gratuities when planning y9our budget. Switch to iced tea and save money. Soda isn't good for you anyway. Yeah, I know try telling that to the kids. We don't even buy soda at home any more.
......... Your tip about "bring sodas" will not help as the cruise line will confiscate them when you board the ship.
Carnival allows each guest to bring 12 -12 oz or less, cans of soda onboard.