Two cars with similar lane keeping hardware can behave very differently on the same road. The variation comes from tuning decisions rather than from the sensors themselves.
The system has to decide what a lane is
A forward camera identifies markings and fits a model of the road ahead, estimating curvature and the vehicle's position within the lane.
Roads rarely cooperate. Markings fade, roadworks leave conflicting lines, and junctions interrupt the boundary entirely, so the estimate carries a confidence level.
Each manufacturer sets its own threshold for how confident the system must be before acting, and that single choice explains much of the difference in behaviour.
Intervention style is a deliberate choice
Some systems apply a gentle continuous torque that keeps the car centred, which feels like assistance and requires the driver to work with it.
Others do nothing until the car approaches a marking and then apply a firm corrective input, which feels like an intervention rather than a partnership.
Neither is objectively correct. The first is more comfortable on a motorway, while the second leaves the driver more clearly in charge on a narrow road.
The handover problem shapes the tuning
A system that steers competently most of the time encourages the driver to rely on it, which is precisely what makes an unexpected disengagement dangerous.
Manufacturers therefore build in deliberate limits, requiring hands on the wheel and withdrawing support when confidence falls, sometimes abruptly.
How that withdrawal is communicated, through warnings, resistance or simply going quiet, differs considerably and affects how trustworthy the system feels.
Sensor choice sets the ceiling
A single forward camera can see markings well in good conditions and struggles in heavy rain, low sun and at night on unlit roads.
Adding radar gives reliable distance and closing speed but no information about markings, so the two sensors complement rather than duplicate each other.
Systems that also track the vehicle ahead can continue guiding when markings vanish, which is why some cars behave far better through roadworks than others.
Regulation is narrowing the differences
Assessment bodies and type approval requirements increasingly specify how these systems must behave, including warning strategies and the conditions under which they must operate.
That pressure pushes manufacturers towards common minimum behaviour, though tuning above the minimum remains a matter of engineering judgement and brand character.
Requirements differ by market and are revised regularly, so the same model can behave differently depending on where it was sold.