The safety device required on all new U.S. cars since 2018 that shows a video of the area behind the vehicle is a rearview camera.
The U.S. requirement comes from Federal Motor Vehicle Safety Standard 111, the rear-visibility rule. Vehicles manufactured from May 1, 2018, onward must provide a driver with a specified field of view behind the vehicle during reversing. In ordinary passenger cars, this is normally delivered through a backup camera connected to a dashboard display.
A rearview camera helps reveal pedestrians, cyclists, low objects, and vehicles hidden directly behind the car. It is especially useful because the rear blind zone can be difficult to see through mirrors alone. The camera does not replace checking mirrors or looking around the vehicle.
A blind-spot camera monitors areas beside or behind the vehicle while changing lanes, while a 360-degree camera combines several cameras into a bird’s-eye-style view. Those systems can supplement—but are not the basic device described in the question.