I'm more impressed that phones can get any positional info from beacons. Determining distance to a radio source is hard with any fidelity - light is pretty fas

I'm more impressed that phones can get any positional info from beacons. Determining distance to a radio source is hard with any fidelity - light is pretty fast. So can phones get decent info about distance to any WiFi/bluetooth source, or is there something about beacons?