The understaffed healthcare system works with overworked doctors on the basis that having a tired and overworked doctor is a lot of the times better than having no doctor at all, because (s)he most likely can end up saving more lives than taking with their tired brain. If your operations have a 90% survivability rate it could still be considered a success despite those 10% they end up killing, because 90% is a lot better than 0%.
Meanwhile a tired pilot is more binary, it either can have 100% passenger survivability if things go well or 100% fatality if things go tits up, meaning the risk are too high to take chances.
Meanwhile a tired pilot is more binary, it either can have 100% passenger survivability if things go well or 100% fatality if things go tits up, meaning the risk are too high to take chances.
It's basic game theory.