This is how We The People have set the system up to work.
We give our police the power to utilize force, when they are obstructed or resisted during the course of the exercise of their law enforcement duties.
okay. We also expect them to exercise i wisely. That means you don't take an unarmed child and push her face into the grass because she was crying for her mother.
Incorrect.
She got her face pushed into the grass because she was repeatedly ordered to leave the area and repeatedly refused to obey the order and therefore earned herself a detaining exercise until the police could decide what to do with her.
When she resisted the detaining exercise she crossed a line which allowed the cop to do what he did.
Once you have multiple 'suspects' engaged in refusal to obey orders or actively antagonizing police or even making threatening moves (as those two boys did while the girl was being put down), the cops haven't got time for that touchy-feely shit... and if they make the wrong choice, they die.
We don't pay our police enough to die.