A scale separating driver help from self-driving in set areas.
L2 is a smart cruise-control buddy with learner-driver vibes. L4 is the little airport shuttle doing its route like it owns the place.
They draw the line for control and blame. Most cars today are L2, but robotaxis aim for L4.
Driving AI
L2 is still driver help, and the driver stays responsible.
Robotaxi
L4 often powers driverless taxis in fixed areas.
Physical AI
Autonomous driving is Physical AI on real roads.