If cops don't respond to these situations like they are a real threat then we all blame them for not acting

Literally no one in history has ever held a cop responsible for not shooting someone they weren't certain had a gun. These shootings are a result of police knowing that they can act recklessly because there is no consequence—they can get away if they just say they feared for their life, even if such a fear is utterly baseless. Meanwhile, outside the US, you see cops routinely refusing to use lethal force even when the person actually does have a weapon or claims they do—because they don't teach cops that they're above the law and can execute anyone who twitches a muscle in their presence.