Coyote in some areas (like mine) are considered a nuisance to livestock. Killing them humane or not is not typically a concern in my neck of the woods. Dead is dead no matter how it is brought about. I am sure that If given the choice a hunter would shoot for the vital or head. However if you've hunted much coyote you'd know they aren't animals to move slowly. Sometimes a shot on the move is all you are presented with and so the opportunity is taken. As opposed to a deer where if the shot doesn't present itself you don't take it. Not taking that shot on a coyote might cost the landowner hundreds of dollars.
Your beliefs are your own and mine are mine. The country I live in allows me to believe differently than others. I understand your logic and stance on the subject but try and understand that of others as well.