It's my understanding that RFID readers are only effective within a few feet of the card. To track a person would entail the installation of millions and millions of card readers every 20 feet or so. Disabling these readers would be easy. The repair bills would run into the billions, let alone people who simply yank them up by the roots and throw them in the river or on a moving garbage truck.
In other words, it's not practical.
See #29.