Global,
The idea with any commercial operator is to make money. It is said that if a GA operator makes 4% on investment they are doing good.
In part that means that they want pilots who need minimum flying before they are set loose on a money making mission.
To do any training costs in terms of aircraft, competent check/training pilots, fuel, decreased aircraft hours to make money, risks involved in training.
In short what an operator wants is a pilot who has what it takes to make money with minimum check flying, not training. Thus a pilot already trained and capable to fly their aircraft type and can be set loose to make money, safely, is the one who gets the job. Not having to spend time training someone to be capable.
R