Interesting links. Such things as requiring animals to be ID'd for fair entries are not simply black or white.
There have been instances of animals spreading diseases among others at the fair, and carrying to animals back home in most any county or state fairs each year. Certainly not in every fair, but maybe one is too many.
Diseases are less likely to get out of control and do significant damage if there are strong rules followed by ALL participants for the protection of all of them and their animals.
Those buying into the conspiracy type theories have the choice to not take their animals out in public and expose others to the possibility of contagious diseases, nor bring diseases home to their own animals, if they are opposed to ID systems.