Long distance RFID readers are currently used mostly for warehouse inventory tracking. Nowadays you can steer antennas using phased arrays like they use in 5G.
https://www.zebra.com/us/en/products/rfid/rfid-readers.html?...
Although, as I understand it, Flock itself is mostly just looking for Bluetooth, BTLE, TPMS Sensors, and Wifi devices.