Surgeons are generally specialists in one particular area and possibly even specialists within that area (ie: only do knee replacements, etc.). Surgeons get better with experience, it's a skill, and different surgeries are different enough that experience doesn't transfer too much. There's also changes over time in best practices so skills degrade not just due to lack of recent experience. If I remember the best predictor of the outcome of your surgery is how many similar surgeries the doctor does per year.

Nobody's making any points about developers

My gut instinct is that this is incorrect, too, but I don't know enough about surgery to make a compelling argument.

I'd back myself to pick up Ruby (a language I've never touched before) and be productive, more than I'd trust a surgeon who only has experience with heart surgery to operate on my brain. Maybe that's ignorant of me.

Even if a Ruby bug would mean death?

EDIT: I take this back. I missed the point of the argument.

That'd change the risks, sure.

I don't think that's the scenario @jrh206 was talking about, though. Most code written in Ruby doesn't have the sort of immediate risk to life or limb surgeries do.

Those requirements are fairly general.

They don't test for "I've been doing this particularly tricky type of bone biopsy right next to the spinal cord for decades" scenarios.

For non-emergency surgeries it's often a long-term relationship where the same doctor who has seen the patient a few times would be the one operating - so if that particular surgeon isn't available for whatever reason, the planned operation would be rescheduled to a different date with the same doctor, not to a different doctor in the same day.