Accidental Survival happens in a lot of Urban Legends. More appropriately this is called "LUCK," plain and simple.
Some people whose lives are spared in many stories haven't really 'earned' their survival. Stories that involve accidents, murderers and stalkers, animal attacks, freak storms and violent natural elements, etc., often also contain messages about being cautious, planning ahead for emergencies, making good moral decisions...
"Accidental Survival" often happens when the main character has failed to plan ahead, has made bad decisions and hasn't been cautious at all...somehow the person's life is spared, anyway, despite risk-taking behaviors, distractions, short-sightedness, etc.
Sometimes a person survives due to a miscalculation on the part of a stalker, killer or other sort of attacker in an urban legend. Sometimes a 'safe person' or authority figure shows up 'in the nick of time' to save a person who has been careless, forgetful, or cocky in urban legends. In any case, with accidental survival, the character in question (the one in the most danger) doesn't actively save him or herself - the survival/saving happens from an external force.
On occassion, the person in danger hasn't actually done anything wrong and ends up in the wrong place at the right time, thus placing him/ or herself in danger. This is actually quite rare, but can happen in stories/urban legends.
More often, even something as seemingly small and insignificant as a person driving at nighttime - when they've been at a legitimate function and have done no wrong prior to the time of danger - is actually considered a 'mistake' and 'fault' on the part of the person......in other words, the person should have KNOWN to drive during the daytime. A situation like this is found in a few versions of "Don't Flash The Headlights/Gang Initiation" where a person flashes but somehow the "gang" car malfunctions, sparing the life of the person who flashed the headlights. If the 'victim' has survived for such reasons, this is like an accidental survival. A survival that wasn't planned out or made possible by the victim's own skills.
My third entry in the Hubpages Hub Challenge is called "Accidental Survival in Urban Legends."
So far on the hub, I have shown the "Knife in the Briefcase" urban legend - a basic version as well as the "Good Samaritan" version which isn't the same story but is similar in end-result. Both stories contain a man whose briefcase is somehow left in a car. In one version, a woman escapes from a killer 'accidentally' because she is actually forgetful, believe it or not! In a similar story, in the "Good Samaritan" version, a woman is annoyed with a man and acts assertively - then finds out afterward that he was intending on killing her.
Enjoy the hub!