My siblings and I tend to go silent and passive when under extreme pain. Having medical professionals question whether the pain is severe enough for intervention has definitely been a problem as a result. For example, my sister was denied pain medication until after the xray showed multiple fractures in her heel. The stereotype of writhing in pain is really only possible for like 3-5/10 for me. If the pain gets worse I go wide eyed and motionless, and if bad enough, I pass out. I've had precisely 1 PT who was adept at recognizing that manifestation.
Improving recognition of the variety of ways in which pain can manifest is definitely an area that could use improvement.