Probably a bit cheeky of me to contribute as I had my two DCs over 40 years ago! The first was a back to back 48 hour labour ending in a forceps delivery that did an awful lot of damage. I still remember it as clear as yesterday. And that was despite the fact that I had a positive attitude. I never did the screaming moaning bit though because I am too repressed in front of strangers
and was determined to 'woman up' (which may not have helped actually). No epidurals then of course.
My second was the right way round, born at home, only a 12 hour labour. no pain relief needed (despite me having been really nervous that time after my first experience).
So, nothing to do with pain thresholds, nerves etc. - just good old fashioned luck.
I am only posting though to ask if psychoprophylaxis - a method using different breathing patterns to stay on top of contractions is still used? You gradually shift your breathing as contractions get stronger, starting with low level abdominal breathing, switch to chest breathing and later to breathing at throat level.
I found it amazingly helpful in staying in control and working through the contractions in my second labour. I've also used it at the dentist so never need injections for e.g. fillings or anything.
If it has gone out of fashion it may be worth reviving as it could help some women I think. It was called the Lamazze method, though I never bought into the whole tree hugging woo aspect of it, just the breathing.