Hundreds of driverless cabs can now be hired in San Francisco but activists are trying to sabotage them, arguing the city should invest more in public transport
Under the cover of darkness, masked vigilantes stalk the streets of San Francisco, waiting for a victim to emerge through the evening fog.
Armed with a traffic cone, the assailants pounce, placing the apparently harmless item on the bonnet of a strange-looking vehicle covered in cameras, bringing it to a dead stop.
