I live in a suburb of Atlanta and haven't locked my front door during the day in about a decade (since moving from an apartment to a house). The world isn't really as scary as the news makes it seem.
> I... haven't locked my front door during the day
This isn't what people mean when they say they don't lock their doors. I grew up in the country in northeast Ohio. I knew many people who simply never locked their doors, including overnight or even when they weren't home.
I lived in middle-of-nowhere Texas for several years, and I think the only time I ever locked the door to my home was when I left for two weeks at Christmas. If my car didn't automatically lock itself after you get out, I would have left it unlocked as well, with the key lying in the center console.
I live in Brooklyn now. Things are a little different here. My door has a $350 deadbolt lock that -- when it broke and locked me in -- took a locksmith, a serious drill and a couple hardened bits to defeat.
Whether you should lock something and how secure you make it isn't a binary decision - it depends on the value of the thing you're protecting and the likelihood of an attack.
The chance of one trying to get into a house in the middle of nowhere Texas uninvited and getting shot in the face, may serve as a deterrent equal to a $350 lock. I know a few Texans who would totally agree with that statement.
Question is, would it have been that hard to defeat if you were someone who cared absolutely nothing for minimizing damage to the door and door frame? Usually, the answer is not at all.
For most of the time I've been here, I didn't lock them overnight either. My girlfriend takes comfort in that illusion of security though, so I play along.
