I don’t see much of a problem myself so long as it’s actually for safety purposes and not just for detainment purposes at a normal school.

The elementary and middle school I went to had fencing to keep people out of backyards and the street, and a gully in the case of elementary school. Reasonable. Keeps minors safe just in case a car came by if a kid went to grab a ball they accidentally launched into the street or they decide to explore the fully and fall over and hurt themselves because little kids are good at disappearing and hurting themselves, I swear.

High school? Absolutely no idea why the football field had a fence other than keeping people off the property, which was connected to a park.