Or the complacency of wizards, if we're being completely honest. The wizarding world has evolved at its own, slower, pace separate from people who have no magical powers. They're shielded by wards and Statutes of Secrecy, which means the two factions don't mix. It's not said outwardly, but likely that the way they dealt with being hunted was to go into permanent hiding and build a secret society.

[A shitty, flawed, blood supremacist society, but who's arguing? She's trying to not be angry, though with the announcement it's impossible. (And the body remembers the rush of unfettered rage that surged with each spell and hex as they fought for the Tower. Not that she relates the wrath to this man, but she does remember how efficiently he focused them all with strategy and orders.)]

Anyway, it has more than just one school. There are three in Europe alone.