I'm surprised that none of them found it more effective to simply wait a day or two before burying someone who had fallen unconscious for no obvious reason.
These practices predate refrigeration, antibiotics, and -- believe it or not -- the stethoscope (which in its recognizable binaural modern form only dates to the 1850s, and took some years to catch on after being invented). With no easy way to detect a weak heartbeat, you don't want to leave corpses lying around unrefrigerated in summer!
I'm surprised as well; as far as I know, in many places around the world it was standard practice for people in villages to have a dedicated room in which a body would be stored for ~4 days before the burial, to make sure the person is actually dead. That technique was widely known for many centuries, if not millenia.
You don't want a body lying around for a few days spreading whatever they died off.
Apparently plague victims were often buried in haste.