Exactly Pete.

There are two possible outcomes when you give treatment to a patient:

(1) It improves the situation

(2) It makes the situation worse.

If (1), then great. If (2) you're in trouble.

If you're going to do something, it pays to be right.

Therefore it makes sense to have the training that you're more likely to be right.

But on the off chance you're wrong, then you better be prepared to explain why you believed your course of action was reasonable given what you knew at the time, AND was within your scope of training, and hope someone else agrees with you that you were reasonable in your action (this is the essense of the good sam laws).