Livestock passports were introduced into law in 1996 it took many years for them to be implemented into any kind of reasonable electronic tracking system, I worked, on a consultancy basis, with some old colleagues in Scotland on part of the implementation of the livestock passports system around 2000-2003 sadly the organisation we were working for was shut down before completion of the project, although many aspects were implemented.
The fundamental problem was that many farmers records were very sketchy as the poor guys had little time to do all the tracking that the government enforced on them, they had a hard enough time just trying to run their own business without all the additional overheads imposed on them by regulation.
For a long time it has been questionable whether animals were being tracked correctly although I suspect they are now.