Because projectiles don't stop at any particular distance and can reach vehicles with humans which are flying over other humans, all of which were innocent of any spying, and most people are complete shit at judging size and distance when looking at objects in the air. (lots of great examples of this with the mystery drones in nj a while back)

I would like to shoot them down too but then I became 12 and a half years old instead of just 12.

As a policy that has to just apply across the board by default, of course the rule has to simply be be that you can not shoot at things in the air. I have no idea how bird hunting is handled but I bet it simply fails a logic test and shouldn't be allowed for the exact same reasons.

Now a tazer or a net or harpoon, all with physically limited tethers... Well there can be no safety argument about whacking something with a baseball bat, and anything with a tether that isn't rocket powered with 1000 feet of range is basically as safe for legit aircraft as a kid with a bat. IE it doesn't matter how inept the yahoo is, their capacity for harm to others is limited to a few people physically very near them, which is the same danger evrryone is to everyone else all the time.