It's because people don't know the derivations, largely because of educational deficits.
They don't know what oxygen saturation measures, i.e., the percentage of red blood cells with their iron-bearing hemoglobin molecules saturated with oxygen, and they think that because that handy little gadget gives them an answer right away it has something to do with "stat."
They don't know what sugar tongs are because they've never seen them used to place sugar cubes in tea in a civilized manner.
They don't know the proper terms for medications and anatomical/physiological concepts because they were never required to use them properly, or maybe because they never learned them in the first place.
They call them "tarry stools" to rhyme with "Harry," as in "do not tarry or you'll be late," because they don't recognize that digested blood is black and sticky like tar and not something to do with timing; I could go on.