The call-out has been around at least since the early '00s.

Just like all security theater, it's easy enough to get around. All you need is the same looking card and the identifier. Most of the time, that's just the kid's name on the card. Some color code the card by class grade as well.

I know this as I was helping a friend scoop their kiddos up from school, and they just sent me to the school with the card. Nobody questioned who I was. They just saw the card, radioed the name, and the kiddos were waiting at the curb when I eventually crawled up to the spot. Since the kiddos expected me, there was no "who is that guy" situation. Otherwise, just fake a card and get a prize is how lame this setup is

The pre-school my youngest has this. The middle school my oldest goes to is much more relaxed. I'm fine with treating my 4 year old like she can't be trusted to run around alone, but my 11 year old can.

What I'm not fine with is there is no bus service for the 4 year old, we have to drive her (I bike, but it isn't a great route - we have to cross a busy 4 lane)