my girlfriend didnt know what central banks are

Me (23F) and my girlfriend (30F) were talking about my masters in law and what I liked about it because I never really talk about it. I mentioned I learned a lot about central banks and thought it was cool. She proceeded to ask me what that was and initially got it confused with the biggest bank in any given country that you can go and open an account in. I end up explaining they're like banks for banks and that they're governmental agencies that set the interest rate for a currency. She proceeds to google her country's central bank and going oh I guess I've never heard of it. I asked about the Federal Reserve etc. and she still didn't know and I just changed the subject.

I obviously haven't brought up the topic again, but it's weird that a 30 year old wouldn't know what a central banks is, right? She's actually usually well educated and informed, but this really surprised me.