When my daughter was Tboned by another car, she broke both bones in her lower left leg. Adrenaline kicked in...she didn't feel it even when she looked down and saw her foot pointing the wrong way. At the hospital, they took x-rays and came back to her appalled. She had butterfly fractures and the bones were out of line and one end was jammed between the other two ends of bone. They asked her why she wasn't screaming!!! By that time the adrenaline had worn off,, but she looked at them and said "would screaming do any good, or just give me a headache too?"
Pain is ALL relative and has a lot to do with the person's personal pain threshhold and/or personality. Some people are just more stoic than others.
Some are more sensitive to pain than others. It's a mixed bag.
Our family has never made a big deal out of pain. Yes, we know it hurts. Sometimes it's excruciating. Screaming does not help at all.
I was in labor for days (literally) with my first child. I remember my mother looking at me and telling me to shut up. Her exact words: "You aren't dying. And quit saying you can't stand it. If you couldn't stand it, you'd be passed out or dead. Either way it would be quieter in here!"
Mother was SO empathetic! LOL (I ended up having an emergency c-section.)