Robovacuums seem to have hit a sweet spot - they do just enough on their own to justify their costs by saving you time and effort. Solving the corner cases you mentioned is possible, but there is not a strong enough economic incentive for that.
Cars make sharp turns and get into tight spaces on unmarked, uneven surfaces, with pedestrians walking everywhere around the car.
That's what a self-driving car needs to support. All road rules out of the window, tiny roads you canbarely navigate, and due to a festival everything is redirected around and all your maps are useless, you're told to drive a short bit through a park because there's a parade on the road, the only way to tell where you can and can't drive being a nonstandard sign and a police officer telling you.
This is a real life use case of driving, as given in many European towns. For additional difficulty, do a small Weihnachtsmarkt in a rural place, where you'll have the same, but with so much snow you can barely see anything.
There is a physical challenge arising from the form factor, such that your intelligence won't help. Those robots don't do stairs and tight places very well simply because the hardware is that way.
In driving, the robot has the same controls as the human. It can turn the wheels, brake, apply gas. That basic playing field is level.
It's all about how well you make the AI see and understand, and translate that into turning the wheel, changing forward/reverse, and hitting gas/brakes.
(I'm referring to devices/products such as the Roomba.)