[QUOTE=The Dumbest Guy in the Room]
Why the secrecy? We know the US Government is fully aware of the supernatural, so are a lot of influentual English. It’s not much of a stretch to assume most world governments are aware of the vampire menace. I’m not sure what the good guys are acheiving by keeping the public in the dark. Surely it would be better to issue everybody and his dog with a stake, some holy water and a crucifix and keep everybody on their toes.
[/QUOTE]
Others have given “within the story” reasons, but I find the meta-reason more compelling: As *Buffy *was written as a metaphor for High School as Hell, the reason the grownups are in denial is that grownups often *are *in denial about the dangers their kids face. Just like real adults feel overwhelmed about drugs, gangs, date rape, school shooting, frat hazing and other teen ills to the point where they deny their own children are at risk from them, Joss’s adults are in denial about vampires, demons, witches and boyfriends who turn into monsters after you have sex with them. Even when they momentarily break through their self-absorption to notice that something strange is going on, they rationalize it, sometimes to absurd lengths, so they don’t have to deal with the fact that the body count at Sunnydale High is rather alarming.
The first couple of seasons, besides Giles, the only adults who learn about demons do so from Buffy, because the Scooby Gang needs their help (or, like Principal Snyder, they’re Not of the Good, and try to cover things up.) As the kids get older, the adults come to admit they know at least some of what’s going on, and they meet grown-ups who they haven’t told themselves, but still know about the demon world. They find adults (like Rack, the magic-dealer*; Willy the Snitch, etc.) who are benefiting from the demon world. They meet more Watchers and Willow meets the coven in England. Principal Wood knew about Slayers long before he met Buffy, of course. And, of course, the Initiative, but they are literally an underground organization. Over on Angel, there’s Wolfram and Hart, which employees both demons and humans. Eventually, it’s apparent that at least some adults are “in on it”, but are either actively covering things up, are in actual denial, or are in denial in front of the kids. As the kids get older, they are allowed to know that grown-ups knew all along, they just didn’t know what to do about it - or they were actually benefiting from the very things hurting the kids. Kind of like life, no?
*although to be fair, we’re never certain whether Rack is human or demon.