Cameras replacing exterior mirrors have appeared on production vehicles and regulations permitting them exist in several regions. The mirror remains standard almost everywhere, for reasons that are mostly about failure modes.
A mirror has no failure state
Reflection requires no power, no processing and no software, and a mirror continues working with a flat battery, in extreme cold and after a decade of neglect.
A camera system depends on a sensor, a cable, a processor and a display, and any one of them failing removes the driver's view of the adjacent lane.
Regulators approving camera replacements therefore require redundancy and fault detection, which adds cost and complexity to something a mirror provides for nothing.
Latency and dynamic range are genuine problems
A display must refresh fast enough that what the driver sees corresponds to the present, and any delay is dangerous during a lane change.
Cameras also struggle where brightness varies sharply, such as emerging from a tunnel at night with headlights behind, and the processing that compensates introduces its own delay.
Human eyes handle that range naturally, so a mirror presents a scene the driver's vision is already adapted to interpret.
Drivers judge distance differently on a screen
Depth perception in a mirror uses cues the driver has developed over years, including the way the eye refocuses between the mirror and the road.
A flat display at a fixed distance removes some of those cues, and drivers moving between the two systems misjudge closing speeds until they adapt.
Placement inside the cabin also changes where the driver looks, which alters established habits of checking over the shoulder.
The efficiency argument is smaller than it sounds
Replacing protruding mirrors with slim camera housings reduces aerodynamic drag, and the benefit is real at motorway speeds.
But the saving is modest against the cost of the system, its wiring and its displays, and it is largely absent in urban driving.
Manufacturers have consequently offered camera mirrors on premium and commercial vehicles, where either the buyer absorbs the cost or the mileage justifies it.
Regulation and repair economics slow the change
Approval rules differ between markets, so a manufacturer selling globally must engineer a mirror version regardless, which removes much of the saving from standardisation.
Repair costs matter too. A damaged mirror glass is cheap; a damaged camera assembly involves calibration and electronics.
The pattern resembles other cabin technologies, where the electronic version arrives first on expensive vehicles and displaces the mechanical one only when its total cost falls below it.