If you fly really high up, then drop down and go at nearly the speed of sound, and then hit a tank with the plane... you'd expect the tank to be destroyed too, right? But it doesn't. What gives?

I dont think the game counts your plane itself as an enitity that can damage tanks... im sure the game thinks your plane is an enitity that is capable of shooting bullets that damage tanks but cant damage tanks by ramming itself into one.

sometimes, if you smash into a truck, you will damage it or even destroy it, but I rhink you need a quite big plane.

Yeah that is quite stupid, when I was a rookie I tried doing it and it didn't work out.

because war thunder doesnt have good mechanics

Nobody knows

Yea i tried it many times didn't worked but for vehicles its working :)

Just imagine all the noobs crashing cheap tier 1 planes into costly tier 3 tanks... Yeah, not cool

Yeah you're not playing that game to suicide into other players. It would ruin all the fun