You’ve apparently never lived in a small community. I grew up on a farm, we had a lock built into the front door, but no lock on the back door, and not even a place to install a lock on the cellar/basement. Never felt the need to lock the house.
We kept the keys in the cars/trucks/tractors; because if the key was in the ignition, we couldn’t lose them. As kids, we always felt odd using the car locks when we went to the “big city”, as opposed to our little town with a population of 126 souls.
It’s a very calm, safe feeling - knowing that everyone around you is watching out for you, and expecting you to do the same for them.
I have lived in a small community, I just don’t think it is smart to leave your keys in your vehicle and leave your doors unlocked. It is very simple to just lock both when you are away.