Susan Sontag emphasizes (On Photography, page 9) the historic connection between photography and tourism. She tells us that:
photography develops in tandem with one of the most characteristic of modern activities: tourism. For the first time in history, large numbers of people regularly travel out of their habitual environments for short periods of time. It seems positively unnatural to travel for pleasure without taking a camera along. Photographs will offer indisputable evidence that the trip was made, that the program was carried out, that fun was had. Photographs document sequences of consumption carried on outside the view of family, friends, neighbors.Though there are certainly numerous other reasons for taking photographs, or situations in which doing so is called for, the reality of being out of our element, of encountering something new, and of experiencing the new without people whom we might ordinarily experience things, makes a vacation a logical time/place to take photographs. I have no idea what percentage of photographs today are taken when people are touring foreign (for them) places. It's my guess that, because so much more or our daily lives are now getting photographed with the ever-present smartphone, tourist photographs have become a smaller percentage of the whole than they were before digital cameras and smartphones, but it's still probably a substantial percentage.