Background checks to see you kid at school?

So there’s been a uproar today in my home town. Today was the elementary schools field day for the end of school, well parents went to the school to watch their kids and were not allowed in. The school claims they sent out a note at the start of the school year that from now on every parent needs a background check in order to enter the school. Most parents claim they have no knowledge of this letter and it has not been enforced all year until now. So all this basically ruined field day because kids were upset their parents weren’t there and parents upset they couldn’t be with their kids.

So obviously the lack of communication was wrong on the schools part, but do you agree with this new background check policy? I’m not sure what types of things would keep someone from being able to enter the school with their kid or how strict they’re going with it.