In most general terms, theoretically, WE shoot to defend ourselves or immediate family/associates. The cop may shoot to defend society: he shoots the fleeing felon if he believes that person is likely to harm society. You and I cannot shoot the perp we come upon who has just raped and murdered our child, if he is fleeing. He is not a threat. The fact he'll do it again does not make us equal to the cops.
I'd say that in many cases, respect was a two way street. But those old line Peace Officers have mostly retired. I miss them. Today, many "serve to Intimidate and Subjugate," and acting as if you believe you are equals is enough to cause a severe escalation of force.
Laws and theory aside, my observations of late suggest that any police shooting is a "good shoot" if the officer involved says the magic words "I was in fear for my life." The exception to this is politics, racial or otherwise. Recently, in Seattle, we had a cop kill a well known local Native American street person woodcarver. From accounts by the few witnesses not yet intimidated or silenced, it appears the shootee was unaware of the shooter before the fatal bullets hit him from the side, being more than half deaf, usually somewhat beered up and often wearing headphones. The cop yelled at him to drop his small woodcarving knife, then opened fire and killed him, as the carver was moving at right angles to the cop's approach. No threatening actions ever took place. But the ONLY reason this one is not a "good" shoot and the cop will face an inquest and maybe even trial, is that his victim was Native American and the tribe is making a lot of noise. Politics trumps just about everything. Big city Police Chiefs are polticians, and they WILL throw cops to the wolves to make themselves look good.
But in general, yes, the cops can shoot you if they wish. And if there's video recorded of illegal actions on their part, it will disappear or somehow turn out to be damaged (ask the people at that Las Vegas Costco...).
“The police of a State should never be stronger or better armed than the citizenry. An armed citizenry, willing to fight is the foundation of civil freedom.” Heinlein