Technically they are, yes, because they're open to the public.
But the impact of taxis on road traffic in a dense city is comparable to the impact of private cars - perhaps even more so as they're often travelling empty between rides. If every journey which was previously done with a car is done with a taxi, there's no reduction in vehicle traffic - meaning the same problems of congestion and pedestrian safety.
Driverless cars can probably drive closer on highways to increase throughput, but that doesn't really help in cities or residential areas. Ultimately if lots of people shift to driverless taxis to get around, there will be far more vehicles on our streets.
But the impact of taxis on road traffic in a dense city is comparable to the impact of private cars - perhaps even more so as they're often travelling empty between rides. If every journey which was previously done with a car is done with a taxi, there's no reduction in vehicle traffic - meaning the same problems of congestion and pedestrian safety.
Driverless cars can probably drive closer on highways to increase throughput, but that doesn't really help in cities or residential areas. Ultimately if lots of people shift to driverless taxis to get around, there will be far more vehicles on our streets.