Absolutely true, but this is also possible with just about every other technology today. "Bad Apps" can report information about Beacons, GPS, or any other sensor on the phone they have access to.
WiFi is active and yes, wiretapping is possible, at least for locating you. Hardware/software for doing this though is not readily available as far as I can tell.
Finally, iBeacons: very simple software running on a passive BLE device that simply records all BLE UUIDs passing by, that's all!