I interpret that as they lose people all the time, but if you come into the ER with 10 bullet holes in you or after coming to a grinding halt on the freeway after a head on collision, they don't expect you to make it and it's not the sleepy drugs at fault.
Here's a thing humans do: They knew what they meant, but saw an amusing way it could be parsed, and said that, because it's amusing. We all knew what the comment really meant.
There's actually a few ways it could have been meant, or it could have been meant to convey all of them. We all have a pretty good idea in the general sense what they meant, but that amusing reply is also an invitation for the person to elaborate and add nuance.
They probably do. Not all medical procedures have a greater than 50% expected chance of survival, but it still might be better than the alternative. That doesn't necessarily mean the anesthesiologist is the once responsible for the death, nor that anyone is, for that matter.
Yes, because the expected survival rate without surgical intervention is zero. With it, slim, but not zero.