I would like to suggest, if I may, that it might help some of you to see how lack of communication can happen so easily in solving major missing persons and murder cases.
You only need to watch ABC Australian Story titled "The Man Behind The Morcombes" that aired on 20/7/2015 which is still available on their website.
It proves just how many mistakes were made by Police in the case of Daniel Morcombe and how a small town lawyer helped to solve the "biggest criminal investigation in Queensland history".
It just proves that police are only human and can make mistakes like the rest of us!
I have no doubt that mistakes are made and in some instances there is a lack of communication. Just look at the mistake that was announced in the Maria James case yesterday. As you say they are only human.
I just don't think that there was any lack of communication in this instance. The car was sighted and it doesn't seem to have been reported to Police at the time. Even if it was reported, the car wasn't missing and initially it wasn't even stated what car Karen owned or drove.
In addition, I doubt each Police officer has access to every single CS report each and every day, it would take some sort of genius to link these reports together in moments, even days. This is another reason why investigations take time, information has to be linked to each case from many many sources.