Wow...That's terrible!! We virtually have no security at our school at all, but then, firearms are completely illegal here, so the danger of a mass shooting is pretty small, so I guess they figure they don't need it. But you don't think about things like THIS...just a parent assaulting the teacher. We don't even have to sign in to come in. I have to be at the school a lot to decorate for the season or holidays or to prepare events...like wrapping presents for the Sinterklaas celebration, or bring in supplies for the Easter breakfast. They know me and I can just walk in and do what I need to do. I can't even imagine having to sign in, much less BUZZ in!! But I see the necessity of it in your school. Scary!
When our 3 kiddos were born (they're about 3 years and 2 months apart) DWifey worked for an insurance company. I got a nice pay raise at one point, and, as she really didn't like her supervisor, we agreed she would quit and come home when she finally had enough.
A few months later she did. About that time our oldest DD and our DS started attending elementary school (DD in Kindergarten, and DS in an early childhood development program for special needs kiddos - he was born at 1 lb. 4 oz. and was in the NICU for 4.5 months).
A friend suggested a part-time job for DWifey in daycare, which then turned into full-time, with a nice discount for our youngest DDs daycare, and after school care for the 2 oldest.
Anyway, DWifey had to be at work at 6a, so I spent the next 7 years (her employment situation changed later) getting both, then all 3, up, ready, fed, to school, and (when they were really young) walked to class.
I must admit (although I was sometimes late-ish

to the office - no problem from the partners, they were starting families at the time, too) it was a little bittersweet when they told me I didn't need to walk them to class anymore.

Plus, DWifey and I were involved in so much school stuff, almost everyone that worked there called us by our first names, especially in elementary school. We were so well-known and trusted we could enter and walk through that school with total freedom.
Even though we were still very involved, trusted, and well-known by school staff in middle and high school, things changed.
By middle school, everyone had to sign in.
In high school, we had to sign in at the office, provide a drivers license, and they copied that onto a sticker that you had to wear at all times while in the school.
I totally get it, but, woof, did we see things change over the years.