How do photographers who print a lot of tourist photos make a profit if not everything they printed is sold? How does their business model work?
There are two main reasons that photographers who print a lot of tourist photos can make a profit. First, postcard publishing is often done on a small-time, local, and niche-orientated level [2]. There's not a lot of money to go round, personal relationships matter, and publishers don't stray far from the niche that works for them [2]. Second, many photographers who sell photography prints sell them as a finished product [3]. This may be a traditional photograph that has been nicely matted and framed [3]. Another popular product is the gallery wrap, which are printed on canvas and stretched over a wooden frame [3]. They have a very high-end artistic look and give your photography art prints another dimension of interest [3]. Overall, photographers who sell a lot of prints can make money because they sell their prints primarily as a finished product or through their personal websites [1, 3]. They can also earn extra cash selling street photography or wedding photography prints [5]. 
While everyone has different business models, some photographers create websites to sell their prints and others use social media to sell their photos [1,2,3]. Some also sell their work through stock photography sites [4,5]. Deciding how to sell photos is a personal choice, but Shootproof has spoken to photographers who make a portion of their income by selling prints either online or in person at flea markets [2,4]. They have also had success using social media to sell their photos [3]. Social media lets photographers target their advertising to people in their geographic location who are interested in certain types of photography [2]. This can boost their business as nothing else can [2].