The door is to stop unhindered and free access into the school without anyone being aware. It’s a stopping point. Then, the next step is that they cannot get in until someone is actually there and aware of their presence and is in the office (which is right next to the door) - and waiting for them to identify themselves.
The office then checks their records for the paperwork signed at the beginning of the year for who is legally allowed to have access to the child.
If someone “blows through” this process - someone is able to call the police immediately and they will be there in a couple of minutes (as a result of someone being aware that they are to check in and being ready to call the police immediately).
That’s how it’s supposed to work.
Then they can do like shops do and put a little bell on it.
The buzzer is there so they can let people they deem not a threat in.
And if they have deemed a person not a threat then the signing in is just a formality.
And the people in the office were upset that rather then her coming to worship at their feet first she went to her child.
The rest of it is just hooey.