I think this is one major problem we are finding out there... many, not all but more than a little, cops are using their own biases and prejudices to determine when a situation is life threatening and when it simply requires stern language. We have seen far too many videos of cops making their own decisions leading to extreme abuse or death.
This is the area where I feel not only training is seriously lacking but so is oversight. If you are going to leave it up to an err prone, possibly biased human being to make the decision on what is life threatening and when they can use force and wehave too many people being executed for minor offenses, then the system needs to be reviewed closer.
Storming a crack house is not the same as confronting someone you pulled over at a traffic stop who has not done anything life threatening. And there is where training and oversight is sorely lacking.
At some point the police need to realize the power they have been given and the ease of abuse and set up a better system to handle the stress, pressure and situational decision making since cops have a license to kill that is very loosely defined.
Someone grabbing your gun and screaming "I will kill you" or coming at you with a knife..seems like on TV a simple case... someone walking away from you or simply walking on the side of a street is not the same but cops sometimes respond way incorrectly and were rarely punished before VIDEO.
Also cops do not have absolute rights of control and there are hundreds of years of court cases trying to clarify and limit what police think they can do. To this day cops are ignorant of it because they train the lawyers but give cops like a Con Crim Pro for Dummies quick training which is useless.