Most ranchers that I know prefer a hide brand to ear tags, especially if the livestock are out in open range land. We still have rustlers out here in the West and swapping ear tags is a quick and easy thing to do when you’re looking to grab some fast money.
I remember reading that only about 90% of Bundy’s cattle were branded (given that no one else’s cattle were mixed in and this year’s offspring were excepted - a reasonable assumption apparently).