> What's the difference in the lawsuit scenario if a doctor messes up?

Scale. Doctors and taxi drivers represent several points of limited liability, whereas an AI would be treating (and thus liable for) all patients. If a hospital treats one hundred patients with ten doctors, and one doctor is negligent, then his patients might sue him; some patients seeing other doctors might sue the hospital if they see his hiring as indicative of broader institutional neglect, but they’d have to prove this in a lawsuit. If this happened with a software-based classifier being used at every major hospital, you’re talking about a class action lawsuit including every possible person who was ever misdiagnosed by the software; it’s a much more obvious candidate for a class action because the software company has more money and it was the same thing happening every time, whereas a doctor’s neglect or incompetence is not necessarily indicative of broader neglect or incompetence at an institutional level.

> If there's no regulatory blocks, then I don't see how it doesn't ultimately just become a cost comparison.

To make a fair comparison you’d have to look at how many more people are getting successful interventions due to the AI decreasing the cost of diagnosis.