In an accident what determines what injuries are serious and not?

“The National Definition For Serious Injuries:

•Severe laceration resulting in exposure of underlying tissues/muscle/organs or resulting in significant loss of blood
•Broken or distorted extremity (arm or leg)
•Crush injuries
•Suspected skull, chest, or abdominal injury other than bruises or minor lacerations
•Significant burns (second and third degree burns over 10% or more of the body)
•Unconsciousness when taken from the crash scene
•Paralysis”

https://highways.dot.gov/safety/hsip/spm/national-definition-serious-injuries-mmucc-4th-edition

Apparently it’s caused many problems in the past because everyone seemed to have a different definition or understanding of what should be considered serious injuries, so they needed to establish an official definition. I honestly just assumed it meant anything that required a hospital visit.