It is a way to keep pesky pilots away from busy airports if the units cost too much. Transponders did that decades ago. I want the ADS-B to be so cheap that everybody gets it to use for VFR as well. What good is a new collision avoidance system that only a few are equipped for? The big airports already have a radar system. The rest of us have nothing. ADS-B was invented for places with no radar, like Alaska. But it must be cheap. I only need a two mile transmit range to avoid a collision. A $200 transceiver can do it. The see and avoid system just isn't good enough.