Steering has traditionally been a mechanical chain from the wheel in a driver's hands to the tyres on the road. Replacing that chain with sensors, wires and motors changes what the system can do and what it must now simulate.
What the mechanical link provided
A conventional steering column transmits the driver's input downward and road forces upward through the same components. Feedback is a by-product of the connection rather than a feature that was designed in.
That is why a driver can feel a tyre losing grip, or sense the change in surface under the front wheels, without being told anything.
The link also fixes the relationship between how far the wheel turns and how far the tyres do, which is set by the mechanism's geometry.
Why a fixed ratio is a compromise
A ratio suited to parking makes the car nervous at speed. A ratio suited to a motorway makes low-speed manoeuvring require a great deal of wheel movement.
Engineers have long compromised between the two, or used variable-ratio racks that change the relationship across the wheel's travel.
With no mechanical connection the ratio becomes a software parameter, so a car can be given very quick steering when parking and much slower steering at speed.
Why feedback has to be manufactured
Once the column no longer carries road forces, the wheel would feel entirely inert. A motor is therefore fitted specifically to generate resistance and vibration.
What that motor produces is a designed impression of the road, built from sensor data about steering load, wheel speed and vehicle behaviour.
The engineering challenge is deciding what to reproduce and what to filter. Removing every impact makes the car feel disconnected; passing everything through makes it tiring.
How the system is made fail-safe
A mechanical linkage fails gradually and visibly. An electronic one can fail completely, so redundancy is built in from the start.
Sensors, motors, control units and power supplies are duplicated, and some designs keep a clutch that can reconnect a physical column if the electronics stop responding.
This is also why the technology reached production slowly. The requirement is not that it works, but that it continues to work after any single component has stopped.
What it enables beyond the ratio
Without a column running through the bulkhead, packaging changes. Space ahead of the driver opens up and the same platform can be built for either side of the road more easily.
Assistance systems can also apply steering directly rather than fighting a driver's inputs through a shared mechanism, which makes lane keeping and evasive intervention smoother.
The trade is that steering feel becomes a matter of tuning rather than of physics, and how convincingly a manufacturer tunes it is now part of how the car is judged.