Uhhh. If someone wants their vehicle, and it's in the middle of a block, it's going to take a while to extract it. And with multiple dropoffs and pickups, it could get very complicated. Presumably the system will collect information about intended pickup time, and arrange vehicles accordingly. And maybe it could charge extra for early pickup.
This robot can park your car for you March 14, 2019 https://techcrunch.com/2019/03/14/this-robot-can-park-your-car-for-you/