I have just seen Richard Hammond's Engineering Connections about Hong Kong Chek Lap Kok (built 1998) and afterwards, Big, Bigger, Biggest about London Heathrow Terminal 5 (built 2008).
Quote from Eng. Conn.:
Hong Kong was one of the first airports to replace bar codes with RFID tags to track bags
Quote from BBB:
Even such an advanced [baggage handling] system [as the new one in T5] still relies on good old-fashioned Bar Codescanners.
Which made me think: Bar codes are, as far as I know, standardized by IATA, so luggage can go end-to-end through a multitude of airports on one bar code ("check-through"), but I guess when the first airport switched over to RFID, there wasn't one for RFID, so there's a bit of a hen-egg problem. How did Hong Kong airport assure that all luggage passing through it had an RFID tag?