While the general populace is still arguing with LTO/Stradcom over the implementation of RFID on all vehicles, some of the more progressive (and rich) subdivisions like Greenhills North have already gone ahead and implemented their own version of the RFID system -- for purposes of automatic gate entry.
You will see a big black box in the photo mounted to the pole. Its a big RFID reader. It scans for the RFID sticker which is mounted behind the rear-view mirror of the car. When it detects and validates that the RFID is valid, it opens and gate and lets you in! This allows for a completely unmanned system.
The system does not come cheap. Greenhills North charges P1,000 per RFID sticker. The reading distance is respectable. My estimate is about 3 meters at least. And it can read through the windshield. From my experience, certain windshield material or angle can distort radio waves. Our automatic gate antenna, for example, has problems receiving signal from the remote control when I'm inside our Toyota Altis. I usually have to open the window and stick out my hand so that the antenna can detect the signal. The same is not true for the other cars.