Places like Walgreen's require a release just as a means to protect themselves, period.
According to my very good friend who is a professional photographer, if you had a picture taken of you on a ship and bought the picture, it is yours to use without infringing on any copyright laws as long as you are not reproducing it for commercial purposes. According to the United States Fair Use Doctrine, you have the right to use that photo for your own purpose. This is why online companies will accept a digital picture and make it bigger or put it on canvas, etc, as long as you stipulate that you are not doing so for commercial gain unless you have the copyright on the original picture. The only exception to this is if the photographer stamped on the back of the picture that it is copyrighted and cannot be reproduced in any manner for any reason without specific written permission. But he said in today's electronic environment, it is widely accepted that you may scan the picture and reproduce it on your facebook page, website, etc. or make a copy for personal use as long as you're not selling it.