Looks like from what the report made by CNN, one of the reporters did a walk though with court Jury members though the building. Based on the report of the the mass shooting at the school it appears it did not have any kind of door access security card sliders or number punch in key pads.
Anyone know if this is common in most schools in the united States?

I visited one college campus in Washington its doors have security access card security.

Also anyone heard of Computer Vision Ai "I am learning the code but its difficult" can be used to detect weapons that are pulled and it can alert security or, lock doors?

I have some sample of code and its only used for Long guns. It sees it, draws a box around the image of the gun. I included some Audio code so it work but its VERY CPU intensive so the streaming video is stuck in ram and the video processing is VERY slow.

Tried to use it on another video where criminals are pulling guns in a convenience store, but it did not work.

As a locksmith for the past 5 years, we deal with a lot of schools. Fortunately the ones around here generally have classroom intruder locks, which lock with a key from the inside.
The school in Texas apparently had a lot of stuff that was not functioning, but also had locks where you can only lock/unlock with a key from the outside. This was initially done so kids could not lock the teacher out of the room.
There is also the issue of free egress.

Nothing more important.

Another example, when setting up a FACP to control the doors at a Bank after hours...do you want the mag locks to release the door in the event of smoke detection or is that a bad idea?

maglocks are fail safe - they require power to stay locked. They are supposed to be hooked to the fire alarm system, so upon alarm activation they will release power.

Hence, FACP.

I graduated High School almost 50 years ago. In those days, the doors were locked at 8:30 AM. If you hadn't made it to school by then, you had to ring a door bell and show ID to get into the building. All the doors had crash bars for emergency egress. Nobody ever got trapped INSIDE the school building, burning or not.

Wasn't a problem then, shouldn't be a problem now.