And you won’t need to park cars on valuable street area. Ideally they’d only stop to load/unload passengers, or to charge. That would free up many more lanes on city streets.
A lane, maybe, some of the time. And don't underestimate the impact of pick up/drop off. Uber was supposed to bring the same change, but not it just takes twice as long to get through Capitol Hill because it's crowded with ubers waiting on pickups.