I find that comment interesting because it talks about the culture shaping the citizens but ignores entirely that culture also shapes police officers. So citizens are violent and aggressive and that must be why police officers react the way they do, not because police officers are also citizens and therefore have just the same chance to be violent or aggressive, if not more since they actively chose a profession where they have to regularly get into violent confrontations?
That's not an accurate reading of the post; it doesn't "ignore entirely that culture also shapes police officers". One of the main points of the post is that
neither police officers nor citizens are exempt from culture's impact. After the poster's description of American culture, he states "Any US officer
grew up in this culture" in an effort to show that they're far from immune from its influence, and he even says that the difference in the behaviour of German and American police officers is the result of having grown up in "different societies". If that's not enough, the poster even concludes that "Everyone is shaped by their environment and the culture and society they grow up in", which, surprise! - includes police officers.
So citizens are violent and aggressive and that must be why police officers react the way they do, not because police officers are also citizens and therefore have just the same chance to be violent or aggressive, if not more since they actively chose a profession where they have to regularly get into violent confrontations?
That's an unfair portrayal of the poster's argument. Sure, he argues that American society has the "Wild West spirit", that citizens are more prone to support vigilante justice, and that guns are more freely available, and that yes, all these factors
explain why American police officers are quicker to pull the trigger than say, German ones. But these factors are not the only factors in police behaviour, and they by no means entail that American police officers are exempt from cultural influence. You seem to think that the poster is claiming that violent and aggressive citizens are the
only cause of increased police aggression, when in fact the poster actually makes repeated references to how the behaviour of police officers is a function not only of increased citizen aggression but
also cultural influence. Violent and aggressive citizens causing police officers to "react the way they do" is not mutually exclusive with what you say in the latter part of your argument, i.e. police officers being "citizens and therefore [having] just the same chance to be violent or aggressive".
The comment says US cops "know about" this culture, not that they participate in it. That entire paragraph was not about how police are part of the culture, but about how the culture is threatening them.
Let's discuss this particular paragraph in the post, which I think is the source of some of your qualms:
"Every US cop knows about this culture of violence, they all know about the inherent distrust of the government. They all know that the threat to their life a real one. You join the Academy and suddenly that threat seems even more real. You are more aware of stories like those officers getting shot in the head while eating lunch. You watch the video of Deputy Dinkheller dying a lonely death behind his patrol car because he hesitated instead of shooting. Your brothers are getting killed out there, every week it seems. It could be you, next time."
Nowhere in this paragraph does it say that the police officer's knowledge of this culture of violence precludes them from participating in it. There is no reference in this paragraph or the other paragraphs supporting the claims you've made. If you think they're true, please offer some arguments in favour for them. I don't see why your knowledge of a culture should prevent you from participating in it, and I've already made clear above in my first paragraph that the poster stated many times that police officers are just as subject to cultural influence as citizens are.
It then talks about the willingness of a citizen to kill, never mentioning the willingness of a police officer to kill except as "their killing is justifiable because citizens are so violent".
Actually, the post does make reference to the willingness of a police officer to kill.
"In Germany, if I was searching for someone who I was told had a gun and I'd find someone matching the description and he started reaching in his waistband, I wouldn't shoot him. I'd wait until I actually saw the gun. Simply because the chance that he actually has a real gun is so, so low.
If I was an officer in the US and I had grown up there, that guy'd be dead as soon as he reached."
And no, it doesn't follow up with a statement that "their killing is justifiable because citizens are so violent". It never comes close to even trying to justify these killings, which leads me to my next point.
Literally the whole point of the comment was to justify why police shoot American citizens.
The main point of the post was not to "justify why police shoot American citizens". It's not meant to excuse the behaviour of American cops; rather, it's meant to explain their behaviour. Nowhere in the post did the author say "and this increased citizen aggression is why it's OK for American cops to shoot citizens!", nor did he even come close to suggesting that the current state of affairs in American society regarding police interactions vis-à-vis citizens is desirable or even justifiable. The post is an explanation, not a justification. Certainly, he says "I'm sure most of you American citizens would react exactly the same in their [police officers] position" but this statement is not close to being a justification for their actions, nor is it even being offered as one. Explaining some of the reasons for increased police aggression in the US is
not the same as defending it, which I think is a key distinction you've failed to make in reading the post.