Jet, I thought you have a thread about advanced robots taking over the universe. I'm sure you have one somewhere.
Perhaps this film clip below better shows how they park the cars while the wheels don't roll, so in fact, they can be in "park". I know the one they're building in Philly lifts the cars by the tires so they don't have to roll at all. Look at the last few seconds of this clip where you can see the clever levers sliding in slots under the tires.