That is VERY technology dependent. Most passive tags must be placed into an active electromagnetic field at a technology characteristic frequency to pick up enough power to charge up a small capacitor and drive the transmission of the embedded numeric code. Employee ID cards tend to work only within 2 to 4 inches. The ones used in retail stores work at a 3 ft distance, thus you find the transmitter/receiver towers placed on either side of a door.
There are active devices placed on the dashboard of a car for billing of HOV lane use. Those have a 30 ft range, but are very large devices. The transceivers typically are mounted on a road sign platform at 15+ ft above the roadway.
Our E-470 tollway has a windshield sticker no bigger than any other RFID and can be read just fine. Highways are now getting all kinds of fancy electronics and I have no doubt that they could read an RFID in your wallet or purse.