I live in Manhattan. The apartment is always deadbolted because the door wouldn’t shut otherwise, but the door to the building is frequently unlocked. When I lived in Brooklyn the lock on the front door to the brownstone I lived in was broken. Nothing ever happened. We were poor college kids, that’s why we didn’t bother fixing it.
My friend who’s stationed in Korea says it’s not unusual to see cars double-parked with the keys left in the ignition so that the stranger whose car is blocked can move the other person’s car out of the way. And this near Seoul, one of the biggest cities in the world!
Usually lock the front door but will leave the back door open all day even if I go out, and all night in warm weather so some breeze gets in.
Mind you, for someone to come in the back door they have to get in the back yard, past 2 dogs and up on the deck.
The car I’m hopeless with. I frequently leave it unlocked in the drive way.
Nth suburbs of Melbourne. Aus.
live in Sydney. never locked a door in my life.
I was visiting my brother in Macon, GA and he and his family have several cars, and they always leave them unlocked in the driveway. Me, being from Chicago, locked my car during my entire week’s stay. It’s just a habit of mine. I wouldn’t feel comfortable leaving my car doors unlocked.
The funny part is that about midway through my visit, some thieves hit during the night. All the cars had stuff stolen from them, except for mine. My car was locked.
So I guess the city slicker knew better this time. I graciously avoided gloating, and made all the necessary expressions of sympathy.
I lock up where I am. Crime is fairly low but I still do it.
I live in a small neighborhood in a small town, near a small school.
I only lock the house when we’re home, because the dogs are in the house with us and I don’t want someone dropping by and letting them escape. I’m considering getting new locks because I actually don’t know where the keys are.
When my dog was lost for several days, I left my front door wide open all the time in hopes he would return. I had to ask my neighbors to stop locking up for me while I was gone. 
House is locked when I am away, and locked when I am at home.
Car is locked when I am not in it. Come to think of it, it locks automatically when I turn it on too.
ETA: I live in a city near Las Vegas, NV.
Glens Falls, NY
I never lock my car or apartment doors unless I am going to be away for an extended period of time.
House and truck both locked.
The truck would probably be okay, we’re in a very quiet neighborhood but you never know who may pass through.
When I lived in the country I seldom locked my house and the basement door was always unlocked. I had big dogs though. Once all my neighbors were robbed (teenaged brat next door) but my house was skipped. My neighbors were a little disappointed, they figured if I had been robbed there would have been a trail of blood to the culprit.
When I lived in Baltimore, my neighbors got robbed while they were working in the backyard. Somebody walked in the unlocked front door. I’ve known women to have their purses stolen off the passenger seat while they were sitting at a red light.
Berkeley, CA and hell no. I just had my front gate re-hung and a mail slot put in the fence so I can more regularly lock that for another minor layer of security. My neighborhood isn’t overall shitty per se, but it certainly has its scattered shitty elements.
Since we live in the middle of Nowhere, USA we don’t do much locking up. I realize it can make sense to do this but I don’t think I even have a house key - If my wife locked the house I’d be SOL.
10 years in upstate NY followed by 22 years in STL burbs, almost never locked cars or doors. However when we first moved to big city STL I was a bit nervous and locked the house doors and made my latch-key kids carry keys. They kept losing them, at least once per week, and I chastised them for doing so. So a few months go by and no “lost” keys, so I praise them for becoming more responsible. They respond: “Oh, we just unlocked the sliding door in the basement and don’t need a key anymore.”:smack: I gave up on the door locking then.
I grew up in a city; so our apartment door was always locked. Even when I moved to a low crime town, and now in the basically crime free boonies, I still lock doors and cars. I even lock my car door in the locked garage. :smack:
We live in a very rural area. If we had to lock the house, we couldn’t; we have no keys. For a long while I was driving soft top Jeep Wranglers. I left the key in the ignition, since someone could “break in” so easily anyway.
My current vehicle I lock and take the keys.The remote turns on lights, etc which is nice.
I once lived in a neighbourhood adjacent to a penitentiary. Upon moving into the neighbourhood , the guy next door advised me to leave the keys in the car pointing to the street.
We lived in a fairly average income town in the Boston suburbs. Never locked the back slider to the deck for the first seven years. Then our neighbors’ cute little granddaughter grew up into a teenager from hell dealing drugs out the shed in their backyard. No more unlocked doors or cars. No more kids playing in the cup-de-sac. And as of six months ago, no more us. The folks who bought our house had a huge gun collection. They invited the grandparents next door for a visit, showed them the guns, mentioned that they don’t plan on taking any nonsense from anyone. Teenager from hell moved to live with her druggie mom.
I live in a small town just outside of Nashville.
My vehicle is locked whenever it’s parked. Something I learned when living across from a rural high school years ago.
I deadbolt the front door to the apartment when coming or going most of the time. The only exceptions are when running laundry up and down the steps. The kitchen door is unlocked whenever I’m home and awake. Locked all other times, even though it would require climbing to a second floor balcony to get in from the outside.
When I was single, I got my loving where I could; I didn’t worry much about nuances like that. But to each his own. 
The wife and I lock our house when we’re away and at night; when we’re home during the daytime we don’t worry about it. Crime in our Maryland exurb of DC is when someone smashes some mailboxes. And we only lock our cars in the driveway if we’re about to leave on a trip, and sometimes we forget even then. Fourteen years here, and nothing’s been stolen from them yet.