how, here's how
Have you ever been driving your family on the motorway, and all of a sudden thought 'How the hell have we travelled that last half mile without hitting anything', then you think hard about the periods of time you just didn't pay proper attention to the road ahead. Try shutting your eyes for even 3 seconds(don't) because I bet many of us aren't attentive for at least that from time to time, and after all we do have a valuable cargo on board don't we? Thats how quickly things can 'get away' from you in a car at 70mph.
If your 'passengers' in the car are wrapped up in a conversation they're not going to notice.
I hope this low tech analogy makes a bit of sense.