My grandfather lives on a farm outside a small town that is all white. Said town is about 3 hours away from anywhere you'd expect to find groids. Neither my grandfather nor any of his neighbors leave their doors unlocked. There are places called reserves where natives live and occasionally try to drive to the city. They don't have enough money for gas so have to steal along the way. It might only happen once every few years, but hearing someone try to open your door gives you time to get your gun, a lot more time than suddenly having 5 guys run into your house. Always lock your door.