If you are in Canada, then....
The taxpayer has not paid for tags or infrastructure in the beef industry other than some developmental grants.
Tags are purchased by producers with a surcharge, and the surcharge funds the CCIA.
Tag numbers are tied to a purchaser, and by law must be in place prior to the animal leaving the herd of origin.
There should be a lot of information on
http://www.canadaid.com
The legislation that empowers the the ID program is enforced by CFIA.
The program was put in place in concern over a disease outbreak such as FMD. Canada also has a zoning window at West Hawk Lake, which is basically a point in northern Ontario where all transit can be stopped. This further allows CFIA to regionalize any potential outbreaks.
Canada is largely export dependent (look at canfax.ca or search beef fast facts). Past experience with FMD in the 1950s also certainly provided some fodder for this decision.
There is a lot of disagreement about approaches, cost, uses of the system etc. at the moment. You mights also want to look up BIXS (Beef Information Exchange System) for some information on developments to use RFID tags for more than just traceability.