My child wanted to watch an animated green lantern series recently so we checked it out. Of course the main character who is the human green lantern is a fighter pilot who does a bunch of sweet fighter pilot flight maneuvers in the opening sequence. I told my child that shows like this often show the military being cool and doing cool stuff, but that in real life what fighter pilots actually do is drop bombs on children. I'm only human, I also enjoy (some) military action movies, but I know it's cotton candy brain poison too.
I hate how many children's shows have pro military pro cop propaganda. How do others talk to their kids about it to inoculate them against brainworms? I usually describe the military and the cops as being like a gang of bullies - they do things to make themselves look cool but really they just exist to hurt people and take their shit.
My mom once walked in on me watching Power Rangers, as a kid. I loved Voltron growing up, and Power Rangers was the closest thing I'd seen on American TV since. I'd really gotten into the first few episodes, but my mom didn't like the show. So she would periodically drop catty remarks. "Don't those outfits look so fake?" "Does this story even make any sense?" "You know they're not in high school, right? All those actors are at least 20 years old."
This ultimately ended up spoiling the show, for me. It did not get me out of my love for cheap cheesy Japanese fighting shows, but it did encourage me to watch shows in my room and avoid my mom at all costs. Not to tell her what I was doing. Growing resentful whenever she asked what I was currently interested in. Being catty in return, whenever I caught her watching her favorite soap opera.
I get that you're not trying to be mean-spirited. But I'll warn you that young kids just don't get the context of any of this. What they do get is that they're excited to see something and you're being a downer. Tolerate the silly kiddy bullshit. See if you can get your kid into more left-leaning silly kiddy bullshit (Avatar the Last Airbender, Legend of the Galactic Heroes, etc). But have your eye towards fun and keep your kid's confidence. Don't spoil your relationship to score a few cheap points.
I know lots of parents often bemoan giving their kids "The Talk", because it really does bring down the curtain on childhood. Nobody wants to have to live with the burden of an armed gang looking for an opportunity to attack you, with the full approval of your neighbors and friends. Don't rush this if you don't have to. Don't inflict anxiety any sooner than you half to.
Which isn't to say you picked a bad time to drop the hammer. But know that what you're doing IS going to cause your kid to have anxiety when they see the police. And in a school with lots of cops, that's a heavy burden for a kid to bare.
Kids are not as tough as you. Be gentle when you can.
Thank you for the thoughtful response. I think there is a difference between belittling like your mom did and warning though. We have age appropriate conversations about colonialism, racism, LGBT issues, veganism already so I'm not sure that this is so dramatically different in tone. The big difference to me is that the military and the cops are massively and explicitly promoted in children's media while the other things I listed are either not mentioned at all or are described in a generally positive (if lib) way. I'd like this to be more like a "safe sex" conversation.