Susan Sontag, On Photography page 9

Most tourists feel compelled to put the camera between themselves and whatever is remarkable that they encounter. Unsure of other responses, they take a picture. This gives shape to experience: stop, take a photograph, and move on. The method especially appeals to people handicapped by a ruthless work ethic--Germans, Japanese, and Americans. Using a camera appeases the anxiety which the work-driven feel about not working when they are on vacation and supposed to be having fun. They have something to do that is like a friendly imitation of work: they can take pictures.