Creating combat vehicles without a turret currently makes the game crash. It just expects one to be there and doesn't check if it doesn't exist. We could potentially patch the game, or override that one function from a DLL so it wouldn't crash, but it'd still be a pain to add the user interface required to add turrets to them. So yeah, "can't" is a bit strong. But this is quite unreasonable. But yeah, I kinda like the idea.