I don’t understand how cars would work on their own with no input from a driver small-scale

I understand being able to type in “Drive to Walmart” and it can back out of your driveway and go to Walmart, but then what? It goes into the parking lot? It finds the first available space? What if you just wanted to go there to pick something up curbside? How can you tell it to go to a specific stall? What if you’re disabled and need to go to the handicap space? How can it tell if your authorized to use that space?

There’s so many little nuances that I don’t understand not being able to have a steering wheel to take control of and manually do things at some point.