They are tipped that way. The decision as to whether to tip at time of service is a personal matter and there is no right or wrong answer. For what it is worth, I normaly tip $1 per drink when I am served, even in the casino where my drinks and those for anyone sailing with me are comped. I only drink sift drinks but I still tip for them. That is what works for me, others will have a wdie varieyu of tipping choices. It all boils down to tip however you are comfortable doing so. Your server will apprecite any tip you give. Have a great time on your cruise. I hope you and all of your fellow cruise members have an absolutely fantastic time.