Our minds are much less logical, consistent, or rational than we like to imagine. The concept of cognitive shortcuts is not new, analytical thinking requires effort and energy, so our minds tend to filter out majority of input and process it subconsciously instead of expending energy on consciously analyzing and processing every little decision. Unfortunately the filtering mechanisms are automatic and kick in even for things that should be considered thoughtfully.
Some further reading on cognitive biases and shortcuts:
- Availability heuristic is the "if you can think of it, it must be important" heuristic, which leads people to fear flying more than driving and terrorism more than flying, even though their chances of dying from a car accident are far higher than ever being involved in a plane crash or a terrorist attack [http://en.wikipedia.org/wiki/Availability_heuristic]