Screenwriters Christopher Markus and Stephen McFeely, the gents who wrote Captain America: The Winter Soldier and are returning to pen Civil War, keep getting asked this question and they’ve got an answer. As quoted by IGN, McFeely told a small group of reporters:
The advancements in technology behind moviemaking have made Superman-worthy leaps and bounds in the past few decades. From motion-capture (which we’ll be seeing a lot of in Avengers: Age of Ultron), IMAX cameras and CGI, filmmakers are able to pull off the effects required of these characters and pull them off right. No wonder that black-and-white Captain Marvel movie didn’t become as domineering as Guardians of the Galaxy.