It's not that microwaves are intrinsically harmful, it's the intensity of the beam. For example microwave ovens operate around 2.4Ghz, same as Bluetooth/WiFi. I

It's not that microwaves are intrinsically harmful, it's the intensity of the beam. For example microwave ovens operate around 2.4Ghz, same as Bluetooth/WiFi. I'm not sure what power delivery operates at. If you get hit by a megawatt beam, you're going to get burned regardless of the wavelength (unless either it's short enough to pass through you, or somehow you reflect 100% of it). As another comment points out, you can beam steer quite fast. You only care about angular rate, and an airliner at cruise altitude moves fairly slowly (eg you can follow it with your eyes easily).