The AHSAA, which is otherwise as advanced as an 8-track player, has had these for a while. I'm a little surprised they aren't everywhere.
It's been almost 20 years since I covered preps, but two of the four states I did high school sports had credentials then. Now, how advanced it was, like did they just hand them out to any person on the street who had a friend at the school who wanted one? I don't know. But they existed and if you didn't have it, it could be a pain in the ass to get access to stuff in those places. That said, I don't remember them at the other two and most places just let you in when you said who you were with. I don't remember ever having an issue.
I agree, though, amazing this isn't common everywhere.