Robotaxi vs driver-assist: the SAE levels
“Self-driving” spans everything from lane-keeping (Level 2) to no-human-needed robotaxis (Level 4). Waymo runs Level 4 in set areas; most consumer “autopilot” is Level 2. The gap is the whole game.
“Self-driving” is one phrase for a wide spectrum, and the SAE levels are the standard way to pin it down. Level 2 is driver assistance: the car steers, brakes and accelerates, but a human must watch the road and take over instantly. Most consumer systems sold as “autopilot” or “full self-driving (supervised)” are Level 2, no matter how capable they feel.
Level 4 is a different thing entirely: within a defined area and conditions, no human driver is needed at all — there may be no one in the driver's seat. Waymo's robotaxis operate at Level 4 in mapped cities.
The leap from Level 2 to Level 4 is not a software update; it is the whole hard problem, because the system must handle every situation itself with no human backstop. Conflating the two is how marketing outruns reality — and why we track paid driverless rides, which only a Level 4 service can offer, rather than vaguer “self-driving” claims.