It's at least conceivable, from my amateur physics knowledge, that the safety issue could be worked around by having a very narrow beam that shuts off if anythi

It's at least conceivable, from my amateur physics knowledge, that the safety issue could be worked around by having a very narrow beam that shuts off if anything interrupts it. The issue I haven't seen anyone mention is that you must have a continuous line-of-sight between receiver and transmitter. Realistically, under real world conditions, how often would you have that long enough for your phone to charge? Either you're using your phone, in which case your hand is covering the back, or you aren't, in which case it's in your pocket or bag. (I'm assuming that the receiver would be integrated with the casing, but the alternative is to have a big bulky thing sticking out the top, which carries its own problems.)