Self-parking systems have started almost a decade ago, and they're almost becoming mainstream these days in premium models.
The BMW i3 is a modern car which also has an optional self-parking system that is cleverly-named Parking Assistant and you don't even need a human to be inside.
It uses a radar-based sensor on the side of the front bumper to detect if the car can fit in a spot. The car can also park by itself. Watch it do the deed in the video below: