It’s true. Custom, i.e. habit, i.e. routine really does change our relationships to things. Doctors and nurses do not flinch when confronted with things the rest of us cannot stomach.
Even receptionists at hospitals get habituated to terrible things. Last time I was at the emergency room, a woman in the lobby was shouting and swearing. She’d shout. Wait a minute. Then start shouting again. But the reception team did not panic. They just rolled their eyes and said it was going to be a long night.