What, exactly, is an Radio Frequency Identification (RFID) Card?
It's a bearer instrument.
Access to my office is controlled by RFID readers. All doors including the rarely used fire escape entrances unlock when touched by an appropriate RFID card. Various interior doors are also controlled in this fashion.
The RFID readers are flat panels with an LED mounted 42" off the floor to accommodate the dwarves that work (or may work) in the building.
At 6' 4", my "rear" pants pocket is about 42" high. I carry an RFID card in a leather ID case in that pocket. To enter the building, I present my rear and the door unlocks. The RFID card never leaves its leather case or my pocket.
The card will open the doors for anyone who presents it. That makes it a bearer instrument in this application.
In practice of course, most photo IDs are bearer instruments since most ID checkers are not very dedicated document examiners.