A robotaxi is a taxi with no one at the wheel, carrying paying passengers within a mapped area. Robotaxis run today mainly in the USA and China, where a few cities allow them. They do not carry passengers on Indian roads. India's Motor Vehicles Act expects a human driver in charge of a vehicle, and the government has said it does not plan to allow driverless cars soon, because they could take away drivers' jobs.
A passenger books the robotaxi in an app, as with any ride-hailing app. The car arrives at the pickup point. Its autonomous driving software decides how to steer, accelerate and brake. The car uses cameras, radar and lidar to see the road. Lidar sends out laser pulses and builds a precise 3D picture of everything around the car. The car also compares what it sees with a detailed HD map of the area.
The key limit is the mapped area. A robotaxi works only inside a zone that has been mapped in detail, and in conditions the software has been tested for. This is why it is described by its level of autonomy. At the level robotaxis use, the car drives itself fully, but only inside that zone. Taking it elsewhere needs new maps and new testing.
Consider a passenger in Phoenix, Arizona, in the USA, who books a ride from an airport to a hotel 12 miles away. The car arrives, the passenger gets in, and the car drives itself through the city. The app shows a fare of about $30, in dollars, and charges the passenger's card. A company monitors the fleet remotely and can help if a car gets stuck.
A robotaxi does away with the driver, who is the biggest cost of a ride-hailing trip. But the cars are expensive, and they need constant mapping and monitoring. The robotaxi is different from a normal car with driver assistance, where a human is still responsible for driving. Indian roads are harder for it than Phoenix, with two-wheelers, pedestrians and animals sharing the lane, and that is one reason Indian companies mainly work on driver assistance for now.