People who throw cigarette butts out of vehicle windows are worse than careless.
They are at best littering. Throwing the butt out the window instead of putting it in an ashtray inside the vehicle is a deliberate act, like throwing candy wrapper or such out – but with the added problem of fire risk.
People smoking in cars often hold the butt outside a window, so the smoke pollutes nearby drivers.
In my opinion ignorance of fire risk should be disqualifying for holding a driver’s licence, as safety around gasoline containers and plumbing should be known.
You should remember cases of cigarette butts being thrown at flag personnel and into a vehicle as road rage.
The lack of an ashtray is not an excuse, they can be retrofitted. A butt bucket or a tall glass of water could fit in a cup-holder.
Or, better yet, stop the filthy, expensive habit.