Your missing my point entirely,
If somebody was to leave her car at a GO Station like you suggest, then maybe LE would begin a more thorough search of the Bain house, something they might have been trying to avoid,
During that search, maybe other "things" or "items" might have been discovered, that somebody was trying to conceal or hide,
Maybe there were blood stains in the house, for an example,
With a crime scene "planted" elsewhere, there is no reason to search the house,
I understand where you are coming from, but I don't think you quite follow how the police work. If the person is considered an adult, thus over 18, the police only do a cursory look for a reported disappearance unless they have reason to believe there was serious danger for the person. You just have to look at the Tess Richey incident to see that.
Now if a car is found at a GO Station and if you believe the family was involved, do you think the family would insist she didn't just run away? You would go right along with the idea she ran away and the police would never look in your house.
There are so many runaways and disappearances reported every single day to police agencies all over that adults fall down the list of priorities. That's sad, but that is the reality.