Games featuring real photos on their cover-art are of a special sort. Throughout time, they have often appeared in relation to sports and movie tie-in games, and have only rarely appeared on other games' covers.
Cover arts using real photos can be split into three broad categories:
These games are often mimicking real-world events and therefore include a lot of real persons. People who are interested in these games are often interested in the associated sport as well, and most likely know some of the players' names. Therefore it is reasonable that the game covers often feature pictures of high-profile sports-players to draw in more buyers. If the cover features a person they know or like, they're more likely to buy the game.
These games are often released at the same time as their corresponding movie hits the cinemas, and therefore often features a cover that resembles the movie's poster-art. The matching cover and poster art makes the products seem to fit together as one unit, which often leads to regrettable purchases by people who really liked the movie and thought the game would be of the same standard. However, this is rarely the case since most movie tie-in games are rushed to completion to hit the movie's release date, so they can cash-in all the extra money from people who liked the movie.
This category is for games that can't be placed in one of the previous two categories. Frequently this can occur with budget titles or games seeking to achieve humorous or artistic effect. Super Nintendo space shoot-em-up Phalanx, for example, sports a jovial banjo-plucking gentleman on its cover who has nothing whatsoever to do with the content of the game, but may still be the most notable thing about it.