While parked or double parked cars can get in the way of emergency service vehicles (that seems to have been the case here with an unoccupied police car contributing to the blockage together with the two Cruise cars), in most cases human drivers will be in the car and can generally be cleared out with the use of a siren.

As to Cruise cars themselves, it's been happening often enough that SF emergency services have been repeatedly complaining about it.

In defense of Cruise though, the pedestrian that died here was struck by a human-driven vehicle, and presumably such pedestrian strikes would be a lot less common if human drivers were replaced by Cruise cars.