Actually we have the highest prison population in the world by far both in raw numbers and per capita. We have roughly 25% of the worlds prison population while having a bit over 4% of the world's population. We really really love putting people in jail for very long periods in the US.
The DA in the OP is definitely an outlier and not the norm. The norm is they charge them with a dozen or more crimes so the person is looking at 60 years in jail and then offer them a plea deal for 5 or 10 years. I'm not just talking about these particular assholes BTW, they actually deserve it, but just about every poor bastard that is caught up in the criminal justice system for whatever reason. The last thing a DA wants to do is actually bring a case to trial so they overcharge the shit out of you, tell you that if you take it to trial they will go for the maximum of 60 years (or whatever) but if you take the plea bargain you will only get 5 years. There are a ton of innocent people who have taken plea bargains, granted not all of them resulted in jail time but still a criminal record, because of the insane amount of time they would face if they lost at trial.
Considering all of the above, I find it really hard to believe that the DA couldn't charge these guys.