foswillruletheworld, the thing is that they look for a specific personality profile that they deem adequate for the job.
Of course, judging that profile from psychometric tests and a 30 minute interview alone, will eventually have some collateral damage.
I have some friends who I consider among the best pilots/professionals/people I have ever come across that didn't make it through day 3.
On the other hand, I have some other friends who made up all the answers to the "tell me about a time when" questions and got the job.
HR will always be an imperfect system...