As mentioned in another recent post, we used to always leave our doors unlocked as a kid.
Now, I lock my doors every day when I leave but if I forget, I wouldn't bother to turn the car around to fix it. If I forget to lock them at night, I also wouldn't bother getting out of bed to do that either.
Of course, I live in the country, about 30 minutes out from our 1 small city, in Canada's smallest and most laid back province.
It's certainly no utopia anymore, crime is starting to become more of a factor but it sure beats being in a big city.