Jaclyn said "factory", not "showroom". I believe that the ST does not have the wiring for the backup camera, and it's probably not in a convenient place to add once the car is fully assembled.
However, I'm sure you could add it if you really, really wanted it badly enough. Might cost a pretty penny to take enough of the car apart to wire up the camera, and maybe do some custom work on the differing ST body panels. Labor will swamp the price of the camera itself.