The moment you permit someone entry into the building without identifying them, you undermine your own security.
Sadly, the idiocy of not identifying someone before permitting them access will almost certainly continue to be practiced (and be defended) until tragedy strikes and someone who is buzzed in reveals his or her criminal intent—with tragic consequences.
You would have to actually construct the building differently to change that. These buildings were built many years before it became such an issue with schools and security.
In my day ... in school ... parents could come right in, unhindered, go to the classroom and proceed to beat up the teacher - which happened a few times at my school. Heck ... on my first day of school, I narrowly missed being shot (left the area of gathering for students), and someone else was shot and killed, with a few others wounded. That was back in 1964. The principal got beat up a time or two, also ... :-) ...
Things are different these days. And if this was a newer building, the structure might be built differently.
Under the present circumstances, I would say a cop at the door would be a good addition, who could then insure that no one would get past without going to the office. But even then, the people in the office aren’t keeping shotguns under the desk or guns on their belts - so if you’ve got a real criminally crazed person ... the police are going to have to deal with it.
This security that is in effect now is to make sure the right person has access to the child and not to stop determined and armed criminals.