Actually, the C class or below shooters are the ones that are more careful of holstering and doing it slower. the B class and above shooters are the ones more complacent and not paying attention to holstering.
When playing in our sport, you are expected to be safe. I would not recommend a new shooter to play in our sport. having finger outside the trigger guard should be second nature, not naturally on the trigger as you say.
So I disagree that anything more than "make ready" is necessary. When I RO, I do watch the gun go into the holster and if I see finger in the trigger and/or the safety is off, I will remind the shooter if there is time...so far so good...I just saved somebody from a DQ this past weekend because he forgot to put his safety on prior to putting it in the holster...