Rather than it being the place where a practitioner works? ("someone whose regular work has involved a lot of training")
But even without this, the thing is, when you don't know, you will make mistakes.
And when your job is to take care of people, mistakes hurt them.
It's the nature of things.
Last year I had 3 medical errors, one that almost got me killed, by very well-meaning professionals.
Closing your eyes and pretending it doesn't happen is naive at best.
But people have to start somewhere. They can't stay in theory forever. And no amount of preparation will save you from making terrible mistakes.
Since we can't put an experienced doctor behind every intern 24/7, there is no real solution to this for now.
Same for programming.