Enough With Amnesiac Doctors

Why did it seem to me when I watched the movie Just Like Heaven a few months ago that I had seen so many times before in other movies scenes similar to the one in which the amnesiac person encounters someone having a medical emergency, immediately knows what procedures must be performed to save the person's life, and then is all "Oh wow, I guess I must be a doctor!" Is this actually a common thing in films or does it just feel terribly familiar? The whole "amnesiac is a doctor" thing feels like a cliche.

You know what I would love to see in a movie?

Our amnesiac protagonist is sitting on a park bench, depressed and confused and alone. (Alone, you know? Film amnesiacs seem to pick up a larger cadre of good friends in 10 minutes of screen time than the average normal person does in a year. If I were to meet a person claiming not to know who he was, etc., I would probably think he is a liar, a conman, or just crazy. At best I would help him get into a cab to a hospital. I don't think I'd be inviting him with me to dinner where he could conveniently be available to perform an emergency tracheoctomy on a fellow diner and thereby reveal himself to be a surgeon.)

Anyway, our amnesiac is alone and unhappy and feeling sort of hopeless. But then another person sits down on the other end of the park bench while talking desperately on their cell phone - "I can't figure this out. I've looked at it a dozen times and the balance continues to be off by $90. I'm at the end of my rope on this!" The person hangs up, and our protagonist cannot help but say:

"When you find your balance is off by an amount divisible by 9, it is almost always the result of transposing numbers. If you are off by $90, you should recheck your ledger for a place where you wrote down 540 instead of 450, or vice versa. It's always good to keep the 'Rule of Nine' in mind in these situations."

"Thanks, that's great advice! Are you an accountant?"

"Uh, I'm not sure actually. Let's see, what are the last four digits of your cell phone number?"

Cautiously, she responds "4562."

"4562, yeah, that's the number of the IRS Depreciation and Amortization form. It's a funny thing about depreciation, actually; people often confuse 5-year and 7-year property..."

The woman suddenly finds herself needing to be somewhere else in a hurry and takes off.

Our protagonist says to himself "I guess I really am an accountant."