The door is locked, yes. So people can't come in. But, even if it's locked, nearly every door got a panic-handle. So, if there's trouble, you come out of the hall with no delay. Also, I think it sound strange, but no big deal in reality and I'm fine with it.
Also the mainentrance to the hall and parkinglots locked, also for safetyreasons. It's easier, to sit in the cong an to know: your car is safe, you can be sure to leave as fast as you can. :D
And anybody knows the moment, you too late and have to ring the doorbell at the cong? When you step inside, all eyes looking at you. I loved it.