If you sit in a parked car in front of a multi-dwelling building, you only see people walk into and out of the building's front door. You don't get to see which

If you sit in a parked car in front of a multi-dwelling building, you only see people walk into and out of the building's front door. You don't get to see which internal unit each person lives in. It doesn't help you to know that I live at 123 Random Street and am not home from 8am-6pm if you don't know that I live in Unit #456. You'd have to first pick me out from the crowd, and then actually follow me into the building to find out which unit I live in. It's much easier to case a location that is directly accessible from the street. And easier to break into a door or window for that location, rather than entering a building and then breaking down a door in a hallway with frequent foot traffic.