The only problem you have shooting anything airborn is that you are shooting uphill with no reference as to where your bullets are going. Are you shooting high or low, taking enough lead or what? If you shoot tracers to correct, the air target knows exactly where you are, not a good situation.
....Bob
Two problems with this argument-
AAA capable of shooting that high is large and prominent, like that 88mm L71. And they require a lot of ammo, hundreds of rounds to get a hit. That was a big gun, and a big target, and a big logistics footprint.
An AAA battery will require a couple of radars to find the target and point the guns, this can’t be done by eye, even in WWII the Germans were using complex integrated radar systems for this. Radar also shouts “shoot here”.
Historically I can’t think of any instances of AAA doing so well. The Germans invested huge amounts in AAA with only moderate success at huge formations on bombing runs. The NVA, for all they put into AAA and SAMs didn’t shoot down that many US aircraft. The Stingers we provided to the muj inflicted casualties on Soviet aircraft, but I’m not aware of it being significat enough to deny the battlespace to Soviet aircraft.
Either weapon can also be defended against as well with time and refitting. That probably won't happen until after a bunch of these craft are knocked out at a critical moment.
More exotic weapons like the ultra-high powered laser or plasma gun could destroy the UAV directly.
It is probably a bad idea to assume that our forces will always have uncontested airspace, clean satellite links, and a technologically unsophisticated opponent.
There is no such thing as an ultimate weapon.