Remember the Eagle Scout shot in the face for trying to undo his seatbelt in order to comply with the order to get out of the car? Or the miliatry man shot multiple times while lying on the ground unarmed
Amother theory might be these SWAT people are just so cowardly they really,really fear being shot even while encased in heavy body armor and bullet resistant masks the homeowner wouldn't have access to; and they shoot out of their fear?
Well, law enforcement in this country has changed from a traditional police, protect and serve thing, to a government para-military force, used against those committing very low level crimes.