I share an apartment with a room mate in a high-security building in Downtown Ft Lauderdale.
One cannot enter without first passing a guard at the front desk, but in order to access the garage one needs a "fob" (a keyless lock device), and again to operate the elevator. There are cameras in all the elevator areas. I feel secure.
But that having been said, I work at night. Sometimes I'm not back home until 4-5 AM. and frequently the roommate forgets to lock the door.
When I lived in a house in a dicey neighborhood, I always locked the door.