The story behind this driver's license is part of movie history. Robert De Niro starred in the classic movie, Taxi Driver. It is about a war veteran who battles his insomnia by becoming a night taxi driver. To get into character, Robert De Niro actually became a licensed taxi driver, which is why this license exists. This isn't unusual for De Niro. In Raging Bull, he actually trained in boxing with Joe Pesci. For Cape Fear, he transformed his body. He got tattoos, bulked up in the gym, and even ground his teeth down.
Taxi Driver has been in the public conversation recently because of the new film, Joker, which many say apes the Taxi Driver film. Joker is based off of the DC villain, but has very little ties to the comic book world.