There is no guarantee that a plane won't drop down from the sky and hit your car either, but, in the case that you mentioned there are thing that you can do to prepare for such a situation. The possibility always exists and not every accident can be avoided, but, constant defensive driving will increase the chances of finding a way to always anticipate something like that. Example... watch the wheels on approaching cars in relation to the line in the road. It is possible to see cars drifting into your lane well before the time they get to you, but, just being aware that this is something to be cautious of can and will prevent a number of accidents.