I've never been in a self-driving car myself, but your position verges on moon-landing denial. They most certainly do exist, and have for a while.
Yes, they still need human backup on occasion, usually to deal with illegal situations caused by other humans. That's definitely the hard part, since it can't be handwaved away as a "simple" technical problem.
AI in radiology faces no such challenges, other than legal and ethical access to training data and clinical trials. Which admittedly can't be handwaved away either.
Waymo claims to have it. Some hackernews comenters too, I started to belive those are Waymo employees or stock owners.
Apart from that I know nobody that has even use or even seen a self driving car.
Self-driving cars are not a thing so you can't say they are more realible than humans.