lol, I was in a tank at the airport last night and some low level with a bounty was able to get into a plane. I thought, well, he got away. He proceeds to fly around me again and again, just out of range. He was probably like "Tee hee, can't catch me MF'er!" He finally comes around and makes a mistake, goes a little low and knocked him out of the sky.
But, on the topic at hand, yes, tanks can wreck cars and not pay. HOWEVER, it is a little glitchy. Sometimes you do. I think there are some specific things like if a tank wrecks a parked car that the player isn't in the tank pays? However, in practice this doesn't always seem to be the case, either.
I've actually downgraded my garage a little bit and mostly drive cheaper cars (9F, Feltzer, Voltic) because of this. I don't want to drive an Adder around anymore and get a 12,500 hit again and again when some single digit lvl player shells me with a tank. The Adder I do have is primarily just going to be used for racing and I don't even do that that much.
I think there's some amazing lower-priced cars in the game, too. I rarely see anyone with a 9F or Voltic (especially the latter, I don't feel like I've ever seen anyone driving the Voltic), both great cars. I don't even feel like I see the Carbo that much. So many Entities and Adders.
I wouldn't be surprised if others do the same thing and you see less Adders and Entities in free roam over time. Players seem to regard both cars as status symbols (like they do chrome, it appears), but after a while of getting hit with the insurance every time the car gets wrecked...
All I can do is remember the good ol' days when I could call for my garage one after another and send every last car into a tank - drop $30-40K in insurance on a tank driver.