Pain tolerance is one possibility. Inner city ER’s that are much more guarded about handing out opiate painkillers due to past abuse is another.
I agree with your first point.
But generally speaking, this is not oxy or Percocet. Opiads are injected into the IV. So abuse in a case of fever and obvious pain (at least what I’ve witnessed) is minimal.
I am betting that some kids tolerate pain differently or they are hesitant to ask for it. I always have had my wife advocating for my kids and me. She never had a problem tracking down a nurse to follow up on stuff.
It’s called the Squeaky Wheel” syndrome.