Could you please provide me with just one single instance of a real tank shooting down a real aircraft with it's main gun?
Its entirely irrelevant, though there is a documented case of a Howitzer shooting down a plane.
"This haunting photograph, which graced every Caribou briefing room, was a grim reminder that the Viet Cong and the NVA were not the only problem for pilots in Vietnam. This incident occurred in August of 1967 when the Caribou (tail number 62-4161) flew into the line of fire of a 155mm howitzer. This was early in the transition of the Caribou from the Army to the Air Force and highlighted the need for far better coordination amongst the services."
Now lets suppose that hypothetically, your argument of "It didn't happen in real lifez, make it stop
!!1" had some actual merit (and it does not, given that it contains two logical fallacies). How exactly do you propose we prevent this from happening, even if there was no historical precedent?
Should tank shells just not damage aircraft? That will never happen, since its gamey as hell, and frankly just downright moronic.
Give them crappier sights? No, their sights are historically accurate. Unless you want your aircraft nerfed for gameplay reasons, tanks won't be any less accurate.
Remove commander mode, or make it so you your turret doesn't follow you at all? No, that won't happen either. Saves HTC a lot of time on GV modeling, and its completely unhistorical, since the commander could give commands to the gunner.
Basically ReVo, you get shot down by a tank's main gun, you are an idiot. And are also an idiot if you think otherwise.