A rear camera is now on every new vehicle sold in the United States. That universality is unusual for a convenience feature, and the reason is that it solves a problem mirrors cannot.
The blind zone behind a vehicle is geometric
Mirrors show what is behind at roughly eye level and beyond. The area directly behind the bumper, close to the ground, is not visible from the driver's seat by any mirror arrangement.
That zone grew as vehicles got taller and their rear ends higher, and as rear glass shrank for styling and structural reasons.
A child or a low obstacle can sit entirely within it, which is the specific hazard the technology addresses and why the concern focused on reversing in driveways.
The camera changes the viewpoint, not the mirror
A camera mounted low at the rear looks along the ground rather than across it, which puts the previously hidden zone squarely in frame.
Wide-angle lenses cover the full width of the vehicle's path, at the cost of distortion that makes distance hard to judge from the image alone.
Overlaid guidelines compensate by giving the driver a reference. Dynamic versions that curve with the steering angle make the projection considerably more useful.
Regulation drove the timeline
Federal rulemaking established a rear visibility requirement that manufacturers had to meet, phased in across model years so production could adapt.
Once compliance was mandatory, the economics inverted. A camera fitted to every vehicle costs far less per unit than one fitted to a small share as an option.
That is why the feature stopped being a differentiator almost immediately and appeared on the least expensive models at the same time as the most expensive.
The screen requirement pulled other features along
A camera needs a display, and once every vehicle had a screen in the dashboard, the marginal cost of adding other screen-based functions fell sharply.
Infotainment systems, phone integration and configuration menus all became cheaper to include because the display was already there for a mandated reason.
The regulation therefore had an effect well beyond visibility, accelerating the shift of vehicle controls onto screens across the whole market.
What cameras still do not solve
A camera shows what is behind at the moment the driver looks. It does not warn about something approaching from the side, which is why cross-traffic alert exists separately.
Lenses foul quickly with road spray, snow and dust, and a dirty lens fails silently rather than announcing that the view is degraded.
The feature also encourages reliance on the screen rather than a physical shoulder check, and mirrors and direct vision remain part of a complete reversing routine.