Who are these people that think fictional high schools are best populated by professional actors in their early- to mid-twenties? We're all so obsessed with our traumatized schooling that it feels good to play-act, "What would happen if I went back with all my adult knowledge and power, but enough makeup to still blend in?" Join us, and suspend your disbelief just a little more: because the SAG can far better fill those roles with experienced adults than to waste their time searching for young people without established careers and plump resumes, who fit the parts, want the parts, and could really, really use the parts. Imperial Britain had court dances, while one of America's essential characteristics seems to be that, for them, high school never ends: it's the lens through which we judge all future selves and events.
Take it, Bruce. "I hope when I get older, I don't sit around watchin' shows about it, but I probably will..."
Yeah, they'll pass you by, but there's always the TV.