If you knew how horrible things can get and how quick it could happen it might change your views on these things.
I think that's why I am so thorough about the measures I have in place to protect my home and, more importantly, my wife and daughter. I use to be blissfully unaware of these things. I specifically remember thinking how unrealistic the safety precautions were around Anthony Hopkins in silence of the lambs. He's just a little guy. You just punch him in the face and it's over. Then I took a job as a prison guard and I met people like him. Not just one. Not just a few, but hundreds.
That's the point that I realized that monsters were real. Not in the scary, beat you with a baseball bat and cut you up kind of way. But in the wait six months for that one time you aren't paying attention, drug you, skin you, and wear your face as a mask for a week kind of way (not a made up story). These people are so far removed from normal thoughts and morality that they might as well be an entirely different species.
Most of the things these people do are kept out of the media. They are too disturbing to report to the public. So most people have no idea these types of people are even out there. They think that people are mostly harmless. They are naturally good and as long as you stay away from the bad parts of town, you're relatively safe. Most of that is just perception though. The average person doesn't come into contact with more than a few crimes per year.
That leaves the news, but they only report the sensational. You don't hear about each individual one of the 16k+ murders per year. The news only shows a few dramatic ones. You don't hear about the 90,000 people that go missing per year and are never found. You don't hear about the million or so times per year a home invasion was successfully and legally stopped with a firearm (technically between 500k and 3m times according to the CDC). They just don't report on these things. Just like I doubt they reported on the druggie you met, or the inmates that I met.
If I'm being honest though, I don't mind the fact that most people don't know how bad things are. It must be nice. It's definitely cheaper. Plus, odds are they'll be just fine. I have just had different experiences. So sometimes I get out of bed in the middle of the night because I don't specifically remember locking the door and I don't want my girls to be murdered...