There could be an interior door and an electrical door closing system ~ JUST LIKE CALIFORNIA!
It is highly presumptuous that the people came down the stairs, opened the main door, and then walked in and got in the car. In fact, that outside stairs could just be an historic facade!
I'm sticking with my BLOWS UP FIRST, BACKS OUT SECOND scenario ~ and that's because the vehicle didn't go into the street ~ with local oxygen consumed, the engine died in a couple of strokes!