The whole building here now has electronic keys rather than the old regular door keys. That happened when our renovations finished. I'm not sure how much the 9/11 attacks or tightened security had to do with any of it: the newspaper has had computer systems and other valuable information it wanted to protect since before that.
We can get out without an electronic key. It's nice sometimes to have the electronic key to get in because I can just wave my purse close to the sensor rather than figuring out which of the many keys on my key ring to use in the dark.
WRT schools, the schools near me have had buzzer systems as long as I can remember. You couldn't get into the school during the school day without pushing the buzzer, telling the secretary who you are, and the secretary letting you in. I suppose a terrorist could impersonate someone or enter when someone else is coming out, but it's unlikely. The buzzer is probably designed more for keeping out salespeople, expelled students, and just keeping tabs on who is and who isn't in the building. In case of a fire, it's good to know who's there and who isn't.
Q: How many poets does it take to change a light bulb? A: 1001...one to change the bulb, 1000 to say it's already been done.