So I've taken it upon myself to answer that very question, with the added bonus of explaining why people who post these things are morons.
First and foremost, the media cannot cover everything at once. There is an entire world of events that happens every single day. Crimes, celebrity appearances, trials, what have you. There is too much going on every day to be able to cover all of it. That isn't the only limiting factor. People don't want to spend all day listening to a list of how and why people got murdered or killed or raped. If you want something like that go read the obituaries. The media cannot cover every brutal crime that happens, they have to pick and choose. Even if they chose something other than the Zimmerman case to report, someone would probably bring up that very case in one of those fucking "Media outrage" posts.
How do they choose? Well yes, a major factor is ratings, news studios do want to report things that bring their viewers back, it is a major factor, but it's not the only factor. Another factor is in the name, people want "new" news. People know soldiers die in Iraq, nobody thinks the military is all fine and dandy. People know they're in a war-torn region and car bombings happen. Call me cold and heartless, but people aren't going to necessarily care if they hear about some nameless soldiers that lose their lives in that region, because that's something we're expecting. And don't get me wrong, people do care about it, but those same people aren't going to be particularly surprised or intrigued when they hear of another car bombing in Afghanistan. What people do want to hear about are the things we aren't expecting.
Also, the news isn't just going to report something everybody agrees upon. They want to report things people are going to disagree about. Let's take this for example
This showed up on my Facebook newsfeed the day of the Zimmerman verdict. Before I go any further, I just want to say my condolences go out to the victims' families of this crime. I'll start by saying, yes this being a black on white crime is probably a factor, but it is most definitely not the only factor. Lets take this scenario. Let's say this is what the media reports this instead of the Trayvon Martin case, here's how the conversation would go.
Me: Hey did you hear about those five blacks that brutally murdered that couple?
Friend: Yea that's pretty shitty
Me: Yea, shame. Wanna grab some lunch?
And here's a conversation I had about the Trayvon Martin case.
Me: Hey you hear about the Trayvon Martin shooting?
Friend: Yea, I wonder what actually happened, Trayvon was unarmed but it was the dead of night, Zimmerman must have been pretty paranoid.
Me: I dunno, it could have easily been a racially motivated murder, I mean how threatening can a black kid with a bag of skittles really be?
Friend: Could he even see his skin? It was the dead of night and the kid was wearing a hoodie, I mean even that is pretty sketchy. I'd be scared.
Me: Dude, I've walked around in the middle of night in a hoodie, it's fucking night man, it gets cold, why wouldn't you wear a hoodie?
Friend: Yea but we live in a pretty safe neighborhood, and plus, this was Florida. Remember when we went to Disney? It doesn't really get cold there ever.
And so on.
The news gives people something to talk about, something to think about. Nobody wants to hear about something that's obviously terrible. People like a little bit of ambiguity, something to contemplate. People want news thats interesting. We know shitty things happen, but a lot of those things aren't very interesting or stimulating.
That's not the only reason the media would avoid that 5-way murder case. That murder is fucking brutal. They made this guy's girlfriend watch as they chopped his dick off and set him on fire before she herself was shot. There's a crowd of mothers that would go absolutely ripshit if you put that on TV. Say what you want about selective media, this is still television, and there's a line you don't really want to cross when reporting. I mean, call me crazy but I don't think people really want to hear about a guy getting his fucking dick chopped off. That's some hardcore "Boo goatse" shit.
No the news isn't perfectly unbiased, yes there are some things that should get reported that don't. But the Zimmerman case is something I want to hear about, because it gives people like me something to talk about, something to think about, and something to post about. The news does keep us informed about the world around us, but you can't expect them to inform you about everything.