Video games go through a wide range of iterations prior to release, and Sega's Crazy Taxi is no exception. Pre-release prototypes exist which show how its development progressed before it was released on Dreamcast.
The website Sega Dreamcast Info has posted information about a version from November 1999, which dates from around a month before the final version was released in Japan. The most notable thing is the expansion of the game's camera options, which were introduced in a previous prototype build from October of the same year.
In the November prototype, it's possible to select from eight different camera perspectives: default, slightly elevated, overhead, static overhead (which can be controlled using the joypad), side-on, front-on and replay. The eight option simply displays a black screen, and is therefore useless.
It's the overhead views which are of most interest, as they give the game a GTA-style feel—and by that, we of course mean the top-down GTA entries prior to the release of GTA III (which, coincidentally, has recently been ported to Dreamcast).
There are other differences to note in this prototype, but the camera views are by far the most interesting. They were removed from the final game.