If I had to guess, I would say that the first airport with CCTV was probably in the UK, since we just love
being monitored. In this instance, Goooogle is not being very helpful. Certainly the first public-facing CCTV system ever installed was here, though.
I doubt there are any laws actually mandating their use. Why would you turn down an opportunity to add an extra level of security? Any laws usually pertain to where you're not
allowed to install them! Note that toilets in schools are fair game these days...
Interestingly, our friends over at Wikipedia tell us that the first CCTV system (of any sort) ever installed was actually at a space
port... well, sort of. It was installed to monitor V2
rocket launches at Peenemunde. How funny.